Bioethics. 2020;34:81–89. | 81wileyonlinelibrary.com/journal/bioe 1 | INTRODUC TION A commonly expressed fear in dystopian novels and popular debates about genetic engineering is that we will produce future people who are exactly alike. But part of the beauty of life is the astonishing di‐ versity that evolution has produced. Of course, evolution has also left us with genetic disorders like Huntington's disease that we'd be better off without. But the difference between eliminating simple genetic disorders and selecting non‐disease genes that influence psychological styles is big. For one thing, important aspects of our psychology ranging from general intelligence to specific personality traits like extraversion are polygenic-they result from many genes with small effects interacting with one another.1 For another, many traits that seem undesirable in some ways are desirable in others. Introversion, for example, may lead to less subjective well‐being than extraversion but also to artistic creation.2 To the extent that some traits might reduce subjective well‐being but have compensat‐ ing individual or social benefits, there are difficult ethical decisions about whether to preserve, reduce, or enhance them. Science fiction raises a legitimate question: how do we preserve a diversity of people in a world in which parents can influence the genetic contributions to their children's personality? This question motivates the article. In Part 2 we review recent research that exam‐ ines the genetic basis of psychological traits, focusing on personality traits and political orientation. In Part 3 we review evidence for the 1 Plomin,	R.,	&	Deary,	I.	J.	(2015).	Genetics	and	intelligence	differences:	Five	special	find‐ ings. Molecular Psychiatry, 20, 98–108. 2 Nettle,	D. (2006).	The	evolution	of	personality	variation in	humans	and	other	animals. American Psychologist,	61,	622–631. Received:	7	June	2018 | Revised:	3	December	2018 | Accepted:	20	December	2018 DOI:	10.1111/bioe.12585 S P E C I A L I S S U E : H U M A N G E R M L I N E E D I T I N G Great minds think different: Preserving cognitive diversity in an age of gene editing Jonathan Anomaly1 | Christopher Gyngell2 | Julian Savulescu3 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2019 The Authors Bioethics	Published	by	John	Wiley	&	Sons	Ltd 1University	of	California	at	San	Diego,	San Diego,	CA,	USA 2University of Melbourne and Melbourne Law School, Victoria, Australia 3Oxford Uehiro Centre for Practical Ethics, University of Oxford, UK Correspondence Jonathan	Anomaly,	Institute	for	Practical Ethics,	University	of	California	at	San	Diego, 9500	Gilman	Drive,	La	Jolla	California 92093, USA Email: anomaly@ucsd.edu Funding information Julian	Savulescu,	through	his	involvement with	the	Murdoch	Children's	Research Institute, received funding through from the	Victorian	State	Government	through the Operational Infrastructure Support (OIS)	Program.	The	Wellcome	Centre	for Ethics	and	Humanities,	Directed	by	Julian Savulescu,	is	supported	by	a	Wellcome Centre	Grant	(203132/Z/16/Z). Abstract It is likely that gene editing technologies will become viable in the current century. As scientists uncover the genetic contribution to personality traits and cognitive styles, parents will face hard choices. Some of these choices will involve trade‐offs from the standpoint of the individual's welfare, while others will involve trade‐offs between what is best for each and what is good for all. Although we think we should generally defer to the informed choices of parents about what kinds of children to create, we argue that decisions to manipulate polygenic psychological traits will be much more ethically	complicated	than	choosing	Mendelian	traits	like	blood	type.	We	end	by	de‐ fending the principle of regulatory parsimony, which holds that when legislation is necessary to prevent serious harms, we should aim for simple rules that apply to all, rather than micro‐managing parental choices that shape the traits of their children. While	we	focus	on	embryo	selection	and	gene	editing,	our	arguments	apply to	all powerful technologies which influence the development of children. K E Y W O R D S cognitive diversity, embryo selection, gene editing, genetic enhancement, regulatory parsimony 82 | ANOMALY et AL. benefits of cognitive diversity for groups, and in Part 4 show how the development of enhancement technologies will lead to trade‐offs for	each	and	moral	dilemmas	for	all.	In	Part	5	we	consider	and	reject the claim that the existence of such trade‐offs generates reasons to abstain from intervening in ways that shape personality traits. In Part	6	we	introduce	our	favored	strategy-regulatory	parsimony. 2 | HERITABILIT Y OF PSYCHOLOGIC AL TR AITS Scientists do not yet understand the precise role that genes play in the development of most psychological traits,3 so our discussion is specula‐ tive. But as the use of technology to select and alter embryos is likely to become ubiquitous, it is worth raising these issues before the science is complete. Behavioral genetics is the systematic study of how genes con‐ tribute to behavior, including behavior associated with personality type. It uses the comparison of monozygotic and dizygotic twins to infer the her‐ itability of traits.4 Behavioral genetics is an indirect way of understanding the genetic underpinnings of behavior in the absence of detailed knowl‐ edge of how genes shape behavior. As computational biology improves, we will learn more about the relationships between specific genetic vari‐ ants and the kinds of behavior they predispose us toward. Although we will focus on the heritability of specific psychologi‐ cal traits we should first emphasize what is arguably the most im‐ portant determinant of health, wealth, and welfare: general intelligence.5 According to a widely shared view in quantitative psy‐ chology, "Intelligence is one of the best predictors of key outcomes such as education and occupational status. People with higher intel‐ ligence tend to have better mental and physical health and fewer ill‐ nesses throughout the life course, and longer lives."6 Intelligence is also correlated with a range of other qualities, including patience and conscientiousness, which have a substantial impact on a host of life outcomes. Higher intelligence is negatively correlated with crime7 and positively correlated with cooperation in strategic interactions that require patience and long‐term planning.8 It appears that intelli‐ gence is an all‐purpose good that many parents will want to enhance in their children, at least up to a point.9 But we want to focus on a neglected topic in the biomedical enhancement debate: specific psy‐ chological traits that are heritable and that may involve trade‐offs with other psychological traits. 2.1 | Personality traits There are a variety of personality types in the human population, and nobody pretends we can neatly divide everyone into a few types. But the Big Five personality inventory is a widely used way to think about personality variation and the heritability of personality traits. The Big Five are openness, conscientiousness, extraversion, agreeableness, and neuroticism. On most accounts, each of the Big Five has a substantial genetic component,	with	genes	accounting	for	an	average	of	about	40–60% of the variation between individuals in a population.10 The heritabil‐ ity	of	general	intelligence	is	closer	to	80%	by	adulthood.11 One impli‐ cation is that while environments matter, genetic influences on personality are powerful. Another is that intelligence and personal‐ ity can be sculpted-if not fully determined-by mate selection, em‐ bryo	selection,	and	(potentially)	genetic	engineering. Extraversion generally has a positive connotation, while neuroti‐ cism has a negative connotation. But these are technical terms in psychology that reflect traits that can be described as good or bad for human welfare only in a broader context. So we should avoid thinking about the ordinary connotations of these terms, or their tendency to increase or reduce reproductive fitness in ancestral conditions, and instead focus on how they are likely to affect the welfare of people in the modern world. In the following few para‐ graphs we summarize some results from an overview of the Big Five by	Daniel	Nettle.12 • Openness is associated with seeking novelty and making associa‐ tions between disparate domains. It is correlated positively with creativity but is also mildly associated with delusion, depression, and even schizophrenia;13 • Conscientiousness is associated with the ability to delay gratifica‐ tion in the pursuit of goals. Conscientious people tend to be good at figuring out how to execute a plan, and they also tend to avoid antisocial behavior; • Extraversion is associated with having an active social life, and seeking out new opportunities. It is also associated with having more sexual partners. These traits confer benefits, but they also tend to increase the risk of danger, and indeed, in the modern 3 We	use	"psychological	traits"	as	a	general	term	that	includes	specific	cognitive	abilities, personality traits, and affective dispositions. 4 The	best	general	discussion	of	heritability	is	Sesardic,	N.	(2005).	Making sense of heritability. Cambridge: Cambridge University Press. 5 Sandberg,	A.,	&	Savulescu,	J.	(2011).	The	social	and	economic	impacts	of	cognitive	en‐ hancement.	In	J.	Savulescu,	R.	Ter	Meulen,	&	G.	Kahane,	(Eds.),	Enhancing human capacities (pp.	92–112).	Oxford:	Wiley‐Blackwell. 6 Plomin	&	Deary,	op	cit.	note	1,	p.	99. 7 Beaver,	K.,	Schwartz,	J.	A.,	Nedelec,	J.	L.,	Connolly,	E.	J.,	Boutwell,	B.	B.,	&	Barnese,	J.	C. (2013). Intelligence is associated with criminal justice processing. Intelligence, 41(5), 277–288. 8 Jones,	G	(2008).	Are	smarter	groups	more	cooperative?	Journal of Economic Behavior and Organization, 68(3–4),	489–497. 9 Apart	from	the	private	reasons	parents	have,	if	general	intelligence	has	positive	network effects, predicting social trust and cooperation, there may be good moral reasons to en‐ hance intelligence (Anomaly & Jones, Cognitive enhancement and network effects; in preparation). 10 Bouchard,	T.	(2004).	Genetic	influence	on	human	psychological	traits.	Current Directions in Psychological Science, 13(4): 148–151; Polderman, T., Benyamin, B., de Leeuw, C. A., Sullivan,	P.	F.,	van	Bochoven,	A.,	Visscher,	P....	Posthuma,	D.	(2015).	Meta‐analysis	of	the heritability of traits based on fifty years of twin studies. Nature Genetics, 47(),	702–712. 11 Haier,	R.	(2016).	The neuroscience of intelligence. Cambridge: Cambridge University Press. 12 Op	cit.	note	2. 13 The	association	seems	to	be	genetic:	Close	relatives	of	schizophrenics	are	more	likely	to be	in	creative	professions.	See	Plomin,	R.	(2018).	Blueprint: How DNA makes us who we are. New	York:	Penguin,	p.	151. | 83ANOMALY et AL. world	extraversion is	positively (though	weakly)	correlated	with being involved in criminal or antisocial behavior; • Agreeableness is associated with empathy and trust, and with harmonious personal relationships. People who score high on conscientiousness and agreeableness tend to be good friends, and good partners in coalitions, in part because they pay atten‐ tion to the needs of others, and can be counted on to stick to the agreements they make. The main downsides to conscientiousness and agreeableness is that they can make an individual liable to exploitation by free riders who seek to manipulate their trust and empathy; • Neuroticism	is	associated	with	negative	emotional	attitudes like fear, guilt, anxiety, and depression. But neuroticism interacts with other traits in positive and negative ways. For example, when neu‐ roticism is paired with intelligence and conscientiousness, it can lead	to	achievement	in	professional	and	academic	settings.	When it is not, or when the environment stifles opportunities to exercise one's abilities, it can lead to crippling anxiety or depression. 2.2 | Pathological personality traits 2.2.1 | Scrupulosity Many personality traits are healthy in moderate amounts but patho‐ logical in large amounts. For example, to the extent that social norms help members of groups coordinate their behavior, it's good for all if each member understands, follows, and enforces social norms. Enforcing a norm may seem like a prisoner's dilemma, as each en‐ forcer bears the cost of identifying and sanctioning those who vio‐ late rules, while the benefits of norm enforcement are dispersed among all members of a group. But natural selection seems to have partially solved the problem by equipping us with moral emotions that	motivate	us	to	follow	norms	and	sanction	norm	violators.	Guilt and shame make us inclined to punish ourselves for flouting socially beneficial rules and indignation leads us to want to punish others who break them.14 But there is natural variation in people's propensity to follow and enforce norms. Some people have a strong propensity to punish rule violators and others have very little inclination to do so. It is socially beneficial to have norm enforcers in a population to promote coop‐ eration. But an extreme version of this personality trait, which psy‐ chopathologists call scrupulosity, occurs when some members of a group obsessively enforce rules, looking to punish every minor viola‐ tion with tough sanctions. This can make the individual who has the quality frustrated, especially when she fails to be able to understand that the spirit of the law is more important than the letter of the law. And it can make the group worse off as it's inefficient to have people devoting every bit of energy obsessing over rules rather than living a productive and happy life. The excessively scrupulous person-an extreme form of con‐ scientiousness-cares too much about social conventions, treating them as intrinsically important and inflexible rather than a mallea‐ ble way of promoting social welfare. On the other side, people who are inclined to flout conventions can benefit a population. As some norms are oppressive, having some non‐conformists in a population will tend to promote social progress even if it's good for most peo‐ ple to follow rules that may increase predictability and harmony. But having an obsessive propensity to follow rules or having no concern for rules at all can be individually crippling and socially harmful. 2.2.2 | Autism The characteristics of some people on the autistic spectrum may be another example of traits that are beneficial in moderate degrees but harmful in extreme degrees. Some of the diagnostic criteria of autism include a tendency to systematize and classify, a severely impaired ability to understand social cues, and relatively low levels of empathy.15 Some researchers have pointed out that these char‐ acteristics can be viewed as an extreme version of the male brain, which tends to excel at systematizing more than empathizing.16 Couples who score relatively high on systematizing are more likely to have children with autistic qualities than those who don't.17 While	severe	forms	of	autism	can	lead	to	a	life	of	dependence	and frustration, some of the genes that contribute to autism may con‐ tribute to a personality profile of someone with especially high abil‐ ity, particularly in engineering and mathematics.18 The presence of these personality traits in our society may contribute to important social goods.19 Some psychologists have distinguished between cognitive em‐ pathy, which allows us to understand what other people are thinking, and affective empathy, which leads us to want to help other people who are in distress. People with low‐functioning autism often score low in both kinds of empathy. Others have challenged this view, ar‐ guing that most autistic people have affective empathy but test low on cognitive empathy.20 2.2.3 | Psychopathy In contrast, psychopaths excel in cognitive empathy, but lack a desire to help others unless it's to their own benefit. According to Simon Baron‐Cohen, "the psychopath is aware that they are hurting someone	because the 'cognitive' (recognition)	element 14 Bowles,	S.,	&	Gintis,	H.	(2011).	A cooperative species.	Princeton,	NJ:	Princeton	University Press. 15 Baron‐Cohen,	S.	(2006).	Two	new	theories	of	autism:	Hyper‐systematizing	and	assorta‐ tive mating. Archives of Disease in Childhood, 91(1),	2–5. 16 Ploeger,	A.,	&	Galis,	F.	(2011).	Evolutionary	approaches	to	autism-an	overview	and	inte‐ gration. McGill Journal of Medicine, 13(2),	38. 17 Op	cit.	note	15. 18 Baron‐Cohen,	S.	(2012).	Zero degrees of empathy: A new theory of human cruelty and kindness.	New	York:	Penguin,	p.	98. 19 Gyngell,	C.,	&	Douglas,	T.	(2018).	Selecting	against	disability:	The	liberal	eugenic	chal‐ lenge and the argument from cognitive diversity. Journal of Applied Philosophy, 35(2), 319–340. 20 Mazza, M., Pino, M. C., Mariano, M., Tempesta, D., Ferrara, M., De Berardis, D., ... Valenti,	M.	(2014).	Affective	and	cognitive	empathy	in	adolescents	with	autistic	spectrum disorder. Frontiers in Human Neuroscience, 7(8),	791. 84 | ANOMALY et AL. of empathy is intact in their case, even if the 'affective' element (the	emotional	response	to	someone	else's	feelings)	is	not".21 Psychopaths are dangerous because they understand how to get what they want, and manipulate others in the process, but don't care about the pain they inflict on other people. Psychopathy is highly her‐ itable and, like most character traits, polygenic.22 At the opposite end of psychopathy, people with very high levels of affective em‐ pathy -strongly influenced by genes and hormones- are more susceptible to anorexia, bipolar disorder, and schizophrenia.23 2.3 | Political orientation It may seem odd to argue that political orientation is heritable. After all, plenty of people hold completely different political views from their parents or siblings. But it is important to under‐ stand that all personality traits are heritable to some degree, and some traits incline us more toward some political ideologies than others.	Jonathan	Haidt	summarizes	the	process	by	saying:	genes make brains, which come pre‐wired with personality traits; traits lead children to take different life paths, and these different paths lead us to construct life narratives that fit a non‐random subset of the available political ideologies.24 This should not be surprising as politics is a human construct: our political ideologies reflect what we care about and how we tend to view the world. In fact, the heritability of political orientation tends to grow after young adults leave home because this is when they have the greatest capacity to seek out and mold environments that accord with their innate predispositions.25 While parents can strongly influ‐ ence their children's political orientation when they're young, these effects tend to dissipate as their children increasingly choose environments and ideologies that match their personality better. In thinking about how genes influence political orientation: [T]he most likely answer is not that attitudes on spe‐ cific issues are heritable, but that issue positions re‐ flect a set of heritable core predispositions, including values and personality traits. These core predisposi‐ tions, which are influenced by life experiences as well as genes, are used by individuals to navigate the so‐ cial, economic, and political worlds and as such serve as the basis for specific attitudes on issues of the day.26 Genes	that	influence	political	orientation	are	an	example	of	genetic factors that affect phenotypes via "outside the skin" pathways.27 They influence the way we move through our social and cultural environ‐ ments, which in turn change the specific values and ideologies we adopt. To some extent, the Big Five correlate with political orientation. For example, a liberal political orientation strongly correlates with the personality trait of openness.28 But the best evidence so far is that political orientation is a separate dimension of personality.29 Like other personality traits, "most researchers consider political traits to be influenced by thousands of genetic markers both indi‐ rectly and through interactions with numerous environmental stim‐ uli and other genes."30 Behavioral geneticists have pointed out that assortative mating- the tendency to choose long‐term mates with similar psychological traits-is especially high for intelligence,31 and may be growing in countries in which women are free to become professionals and where professionals are more likely to marry each other than to marry people with lower status jobs. Perhaps more striking than assortative mating for intelligence, "long‐term	mates	correlate	more	highly	on	political	ideologies	(.65– .71) than	on	almost	any	other	clinical,	behavioral,	or	psychological trait."32 Some worry that an increase in assortative mating for polit‐ ical orientation may exacerbate the political divide.33 But the strong correlation for political orientation may not be as worrisome as it seems. It may be that the correlation between long‐term mates and political orientation is not explained simply by the fact that partners have similar personality traits. It may partly be explained by the fact that in many places political orientation is a kind of ethnic marker, like race and religion. In fact, there is evidence that in the USA today people are at least as likely to discriminate against others of a differ‐ ent political party than against others of a different race or reli‐ gion.34 It is conceivable that quick and accurate gene sequencing 21 Op	cit.	note	18,	p.	85;	Correction	added	on	25	April	2019,	after	first	publication:	The preceding quotation was previously wrong and has been corrected in this version. 22 Tuvblad,	C.,	Bezdjian,	S.,	Raine,	A.,	&	Baker,	L.	A.	(2014).	The	heritability	of	psychopathic personality in	14–15	year	old	twins:	A	multirater,	multimeasure	approach.	Psychological Assessment, 26(3),	704–716. 23 Warrier,	V.,	Toro	R.,	Chakrabarti	B.,	iPSYCH‐Broad	autism	group,	Børglum	A.	D.,	Grove J., ... Baron‐Cohen, S. (2018). Genome‐wide analyses of self‐reported empathy. Translational Psychiatry, 8(1),	35. 24 Haidt,	J.	(2012).	The righteous mind: Why good people are divided by politics and religion. New	York:	Vintage,	Chapter	12. 25 Hatemi,	P.,	&	McDermott,	R.	(2012).	The	genetics	of	politics:	Discovery,	challenges,	and progress. Trends in Genetics, 28(10),	525–533. 26 Funk,	C.,	Smith,	K.	B.,	Alford,	J.	R.,	Hibbing,	M.	V.	Eaton,	N.	R.,	Krueger,	R.	F.	...	&	Hibbing, J. R. (2013). Genetic and environmental transmission of political orientations. Political Psychology, 34(6),	805–819,	p.	806. 27 Kendler,	K.,	&	Ralph,	G.	(2006).	The	nature	of	genetic	influences	on	behavior:	Lessons from "simpler" organisms. American Journal of Psychiatry, 163(10),	1687. 28 Op	cit.	note	24. 29 Hatemi,	P.,	Medland,	S.	E.,	Klemmensen,	R.,	Oskarsson,	S.,	Littvay,	L.,	Dawes,	C.	T.	... Martin,	N.	G.	(2014).	Genetic	influences	on	political	ideologies:	Twin	analyses	of	19	mea‐ sures of political ideologies from five democracies and genome‐wide findings from three populations. Behavioral Genetics, 44(3),	282–294. 30 Op	cit.	note	25,	p.	527. 31 Op	cit.	note	1. 32 Op	cit.	note	25,	p.	527. 33 Alford,	J.,	Funk,	C.	L.,	&	Hibbing,	J.	R.	(2005).	Are	political	orientations	genetically	trans‐ mitted? American Political Science Review, 99(2),	165. 34 Iyengar,	S.,	&	Westwood,	S.	(2015).	Fear	and	loathing	across	party	lines:	New	evidence on group polarization. American Journal of Political Science, 59(3),	690–707. | 85ANOMALY et AL. combined with embryo selection or gene editing technology could increase the genetic basis of existing political divides. We	have	tried	to	give	an	overview	of	how	different	psycholog‐ ical traits are both heritable and capable of producing different life outcomes	and	sociopolitical	arrangements.	We	now	want	to	explore why cognitive diversity is desirable, and what kinds of trade‐offs we might face in selecting or altering embryos to shape our children's traits. 3 | THE VALUE OF COGNITIVE DIVERSIT Y A number of authors have emphasized that if we want to solve a complex problem it is often better to have a cognitively diverse group of people than the same number of very bright people who see the world in a similar way.35 This insight is perhaps best captured by	William	Buckley's	quip	that	he'd	"rather	entrust	the	government of the United States to the first 400 people listed in the Boston tel‐ ephone directory than to the faculty of Harvard University."36 People with different experiences and different cognitive styles (which	arise from	a	confluence	of	psychological traits), look	at the world through different lenses that can complement one another. And as long as they are organized in teams or in groups that com‐ municate and cooperate effectively their different talents can be harnessed to solve complex problems. Apart from simple teamwork, Jonathan Haidt has given some reason to believe that people with diverse cognitive styles may be better at solving political problems.37 For example, people with con‐ servative personalities tend to be skeptical of outsiders and of radi‐ cal new ways of organizing political society and liberals tend to be more open to alternatives to the existing arrangements. A healthy proportion of liberals in a population can help a group learn from outsiders	and	allow	people	to	try	out	new	experiments	in	living	(to paraphrase	John	Stuart	Mill).	But	conservatives	may	have	a	benefi‐ cial influence in pressing the brakes when radical alternatives are likely to expose a group to danger.38 Similarly, cognitive diversity can combine with open societies to produce salutary social effects. Mill argued that even people who are content with the status quo often benefit from new ways of thinking and models of living: Originality is the one thing which unoriginal minds cannot feel the use of [.... But] recollecting that noth‐ ing was ever yet done which someone was not the first to do, and that all good things which exist are the fruits of originality, let them be modest enough to be‐ lieve that there is something still left for it to accom‐ plish, and assure themselves that they are more in need of originality, the less they are conscious of the want.39 While	Mill's	point	is	about	originality	and	eccentricity,	these	are	at least partly shaped by different psychological traits as well as different environments.	Diversity	is	good,	on	this	view,	to	the	extent	that	it	can help us solve political problems and come up with cultural and scien‐ tific	innovations	that	benefit	everyone.	More	recently,	Jerry	Gaus	has extended Mill's insight to argue that some degree of moral diversity, which is tied to cognitive diversity, can help populations solve social and political problems that arise in response to an increasingly complex world.40 It	is	important,	though,	not	to	overplay	this	point.	Radical	di‐ versity of values in a population is likely to undermine trust and impair successful collective action.41 What	is	important	is	that	there	is	some optimum range of diversity.42 Finally, quite apart from their instrumental effects on solving political problems and generating new ideas in the arts and sciences, aesthetic and personality differences can make life more enjoyable (at least within certain parameters: having more psychopaths in the population or people with severe autism is not especially desirable). Given the value	of diversity, and assuming there is some ge‐ netic contribution to it, we want to explore two kinds of trade‐ offs. First, the trade‐offs that parents will face in choosing a child with different traits when they are concerned only with the child's welfare; and second, the trade‐offs parents will face between se‐ lecting or altering children in a way that is likely to affect the wel‐ fare of society more generally. The total effects of such trade‐offs may be small and difficult to predict for any given child. But from a social standpoint, the aggregate effects of many such choices are significant. 4 | ENHANCEMENT DILEMMA S Suppose we gain the power to alter embryos before they develop into	children.	Versions	of	gene	editing	technology	such	as	CRISPR Cas9 already promise to make genetic engineering a reality in the 35 Hong,	L.,	&	Page,	S.	(2004).	Groups	of	diverse	problem	solvers	can	outperform	groups	of high ability problem solvers. Proceedings of the National Academy of Sciences of the United States of America, 101(46),	16385–16389. 36 Wakefield,	D.	(1961).	William	F.	Buckley:	Portrait	of	a	complainer.	New	York:	Esquire. 37 Op	cit.	note	24. 38 Conservatives	also	tend	to	emphasize	values	and	family	structures	that	have	historically fostered above replacement‐level fertility, whereas liberal societies have seen their num‐ bers plummeting to sub‐replacement levels. As Filipe Faria has argued, market liberalism may be creating a self‐defeating pattern of fertility declines in the most prosperous soci‐ eties. This is not necessarily an argument for returning to a more conservative society, but it may be yet another interesting trade‐off between groups comprised of people with different	values	and	cognitive traits.	See	Faria,	F. (2017). Is	market liberalism	adaptive? Journal of Bioeconomics, 19(3),	307–326. 39 Mill,	J.	S.	(1859).	On	Liberty:	Reprinted	in	New	York	by	Penguin,	Chapter	3. 40 Gaus,	G.	(2018).	The	complexity	of	a	diverse	moral	order.	Georgetown Journal of Law and Public Policy, 16(S). 41 Ostrom, E. (2000). Collective action and the evolution of social norms. Journal of Economic Perspectives, 14(3),	137–158. 42 Kahane,	G.,	&	Savulescu,	J.	(2014).	Normal	variation:	Refocusing	the	enhancement	de‐ bate. Bioethics, 29(2),	133–143. 86 | ANOMALY et AL. near future, even if we're a long way off from manipulating poly‐ genic psychological traits.43 Assuming this technology becomes widely available, we will face a number of hard choices. Even if gene editing does not progress, whole genome analysis of embryos is now possible and genetic selection for psychological traits is on the horizon. And there will be other technological and social means of modifying a child's personality (such as pharmaceuticals and medical	devices).	We	will	assume	(rather	than	defend)	two	princi‐ ples: procreative beneficence and procreative altruism. Although there are plenty of philosophical objections to these principles we will take them for granted in order to explore what they might imply about parental choices that may shape the characteristics of children. According to the principle of procreative beneficence44 par‐ ents should select the child, of the children they could have, who is	expected	to	live	the	best	life	possible	(in	terms	of	well‐being), given the available information. According to the principle of pro‐ creative altruism45 prospective parents have a moral reason to have a child whose existence can be expected to contribute more to the well‐being of others than any alternative child they could have.	We	recognize	that	the	two	principles	can	come	into	conflict, and that people who hold both principles will give them different weights.	We	also	recognize	that	procreative	choices	involve	other values, including the interests of parents and family. But we focus on procreative beneficence and altruism to illustrate the kinds of social dilemmas that widespread access to genetic modification and selection could create. We do not assume parents always know all of the relevant risks and benefits of procreative choices but we do assume that they have strong moral reasons to inform themselves of the science and moral trade‐offs their decisions involve. 4.1 | Trade‐offs between mutually exclusive traits As we argued above, some cognitive traits exist on a spectrum and some may be mutually exclusive. For example, some studies suggest that individuals who perform badly on tests that measure latent inhi‐ bition	(an	ability	to	block	out	irrelevant	stimuli)	do	well	on	tests	of creativity, and vice versa.46 In other words, these traits may be to some extent mutually exclusive-people are creative precisely be‐ cause their mind wanders and they cannot block out seemingly ir‐ relevant information.47 Assume it becomes possible to manipulate genes or select em‐ bryos in ways that influence these traits. Parents will face a tough choice. Being able to block out irrelevant details and concentrate is valuable in some circumstances and being creative is valuable in others.	Whether	either	trait is	good	for	someone	is	highly	context dependent. This trade‐off makes it hard to apply procreative benefi‐ cence, as it is difficult for parents to pick the trait that will be overall best for their child. This trade‐off also makes it hard to apply procre‐ ative altruism. It seems likely that society benefits from having a mix of people who are creative and people who have good latent inhibi‐ tion.	Without	knowing	how	other	parents	will	act	it	is	hard	to	know how to promote collective welfare when altering this trait. Other traits may fit this pattern. For example, consider the trade‐off that exists between systemizing and empathy discussed above. Because each end of the spectrum is good in different cir‐ cumstances and we do not know the exact circumstances facing our children, it is difficult to promote individual and collective welfare by	altering	them.	When	we	generalize	from	a	two‐person	game	to a choice faced by billions of people the optimal population mix be‐ comes harder to figure out, and-even if it were discoverable-nearly impossible to achieve. 4.2 | Trade‐offs between individually beneficial traits and collectively beneficial traits Some psychological traits are clearly beneficial to individuals but will be collectively bad if possessed by all. Consider the choice to alter an embryo in a way that makes the child more extraverted. As indicated above, extraversion is heritable and people who score high on meas‐ ures of extraversion tend to have better social relationships, are less prone to depression, and enjoy success in many different profes‐ sions	(most	obviously,	business).	Extraverts	are	likely	to	be	a	bit	hap‐ pier, more effective in communicating to other members of a team, and better public speakers. They are also likely to make more money if their extraversion is combined with conscientiousness and high general intelligence.48 So it seems obvious that most parents moti‐ vated to improve the well‐being of their child would choose to make them extraverted. Yet	it's	also	plausible	that	having	some	introverts	in	a	population is good for collective well‐being. Introverts are especially good at problem‐solving on their own-i.e., synthesizing and distilling infor‐ mation from collaborative work when they are alone.49 To illustrate why a combination of extraverts and introverts can be beneficial, consider the story of Apple Computers. Apple Computers was co‐ founded by an introvert, Steve	Wozniak, and an extravert, Steve Jobs.	Wozniak	was	a	more	traditional	computer	geek-an	introverted systematizer-while	Jobs	was	a	businessman	with	a	creative	vision- an extraverted showman. Both made crucial contributions to the company's success and to the development and adoption of personal computers. Their different cognitive styles worked together to the 43 Op	cit.	note	13,	p.	116. 44 Savulescu,	J.	(2001).	Procreative	beneficence:	Why	we	should	select	the	best	children. Bioethics, 15(5–6),	413–426. 45 Douglas, T., & Devolder, K. (2013). Procreative altruism. Journal of Medicine and Philosophy, 38(4),	400–419. 46 Carson,	S.,	&	Peterson,	J.,	&	Higgins,	D.	(2003).	Decreased	latent	inhibition	is	associated with increased creative achievement in high‐functioning individuals. Journal of Personality and Social Psychology, 85(3),	499–506. 47 Gyngell,	C.,	&	Easteal,	S.	(2015).	Cognitive	diversity	and	moral	enhancement.	Cambridge Quarterly of Healthcare Ethics, 24(1),	66–74. 48 Gensowski, M. (2018). Personality, IQ, and lifetime earnings. Labour Economics, 51, 170–183. 49 Cain,	S.	(2013).	Quiet: The power of introverts in a world that can't stop talking.	New	York: Broadway. | 87ANOMALY et AL. overall benefit of the company, the company's customers and the broader population. The possibility of influencing traits along the introversion‐extra‐ version spectrum is therefore likely to lead to a dilemma between what	is	good	for	each	(procreative	beneficence)	and	what	is	good	for all	(procreative	altruism).	To	the	extent	that	we	think	both	principles matter, regardless of whether we agree about how much they mat‐ ter, this is a deep social dilemma. If everyone acts with the interest of their own children in mind it produces a result that is collectively suboptimal, assuming that procreative altruism has some non‐trivial weight. In	other	words,	what is	good	for	each	may	not	be	best (or even	reasonably	good)	for	all. Similar dilemmas will arise for many other traits. Consider the choice to alter our children's genes to make them more compassion‐ ate than they would otherwise be. If everyone chose to engineer more compassionate (or affectively empathetic) children perhaps violence would decrease and altruism would increase. Other things equal, procreative altruism suggests this would be desirable. But from the standpoint of procreative beneficence there might be trade‐offs for children engineered in this way-for example, more compassionate people might lose some of the drive to achieve great things for themselves, like Olympic medals or artistic creations. However, suppose that a world in which everyone was highly com‐ passionate would be best for all because of increased trust and re‐ duced violence. Assuming this, procreative altruism implies we have reasons to select for highly compassionate children. However, if ev‐ eryone were highly compassionate, this creates an incentive for de‐ fectors. People who are much more selfish than average may be able to thrive, benefiting from the trust and good will of others and giv‐ ing little in return. In these circumstances procreative beneficence would instruct parents to produce children who are less compas‐ sionate. But if everyone acted like this it would be impartially worse for all. There is a coordination problem here. The best impartial re‐ sult, from the standpoint of procreative altruism, can be produced only if everyone acts together-but this is beyond a parent's control. In other words, in these simple and stylized examples there is no reason to expect the set of individual procreative choices to produce a social optimum. And there is no reason to assume that people will converge in their moral judgments about precisely what that opti‐ mum is, even if we can assume everyone will endorse procreative beneficence and procreative altruism. In sum, the ability to alter psy‐ chological traits will expose parents to a range of practical dilem‐ mas involving trade‐offs. This raises the question of how we should regulate and protect cognitive diversity in an age of whole genome analysis, embryo selection, and gene editing. 5 | THE NATUR AL LOT TERY IS UNFAIR In the face of this problem it might be tempting to ban genetic selec‐ tion	or	enhancement.	Even	if	such	a	ban	were	effective	(which	we have reason to doubt, given strong demand and the global reach of black	markets),	this	would	leave	the	balance	of	traits	in	the	hands	of the natural lottery. However, there is no reason to believe that na‐ ture has afforded human populations with optimum levels of diver‐ sity. The current distribution of traits has been shaped by natural selection.	Natural	selection	works	to	promote	the	survival	of indi‐ viduals and genes. It does not aim to promote human well‐being or the collective good. It is clear that nature creates great inequality in traits that are relevant both at the level of personal and social wel‐ fare. There is no good reason to believe that normal human variation is optimal for the outcomes that matter.50 Nor	is	there	good	reason to believe that leaving such choices to parents will be worse. At very least, parents are more likely than the natural lottery to promote their children's well‐being. Furthermore, technological development is rapidly changing the environments to which humans are exposed. The way we interact with our environment today is very different from that just a few centuries ago. This has produced the problem of evolutionary mis‐ match, one version of which occurs when traits that were adaptive in ancestral conditions fail to promote either survival or well‐being in our current environment.51 For example, a person who scores high on neuroticism may very well have produced more surviving off‐ spring, or contributed to the welfare of his tribe in an environment in which predators are a constant threat. Having an extreme fear of bugs or being disposed to worry about whether we've adequately prepared for the long winter ahead would be likely to be rewarded. But high levels of neuroticism today can result in clinical depression or anorexia.52 Natural selection is a slow	process that	works	over several generations. Hence it is unlikely that it has equipped individ‐ uals or populations with the balance of personality traits that best promotes our flourishing today. 6 | REGUL ATORY PARSIMONY There is no way to avoid the questions raised in the previous sec‐ tions. Failing to confront technologies that already enable us to se‐ lect embryos, and will soon allow us to edit them is not a promising strategy, nor does it seem morally justifiable. Thinking about what kinds of people will exist and how we will create them is arguably our most important moral obligation.53 Some authors have argued that when the freedom to choose our children's characteristics creates a collective action problem, there is a prima facie case for government intervention.54 In a sense this is right: we cannot expect undirected private choice magically to produce an optimal distribution of goods 50 Op.	cit	note	42. 51 Cofnas, N. (2016). A teleofunctional account of evolutionary mismatch. Biology and Philosophy, 31,	507–525. 52 Lieberman,	D.	(2013).	The story of the human body.	New	York:	Vintage,	Chapter	7. 53 Savulescu,	J.,	&	Kahane,	G. (2009).	The	moral	obligation	to	produce	children	with	the best chance of the best life. Bioethics, 23(5),	274–290;	Gyngell,	C.,	&	Selgelid,	M.	(2016). Twenty‐first	century	eugenics.	In	L.	Francis	(Ed.),	The Oxford handbook of reproductive ethics	(pp.	141–158).Oxford:	Oxford	University	Press;	Anomaly,	J.	(2018).	Defending	eugen‐ ics: From cryptic choice to conscious selection. Monash Bioethics Review, 35(1–4),	24–35. 54 Gyngell,	C.,	&	Douglas,	T.	(2015).	Stocking	the	genetic	supermarket:	Reproductive	ge‐ netic technologies and collective action problems. Bioethics, 29(4),	241–250. 88 | ANOMALY et AL. in an economy or traits in a population. But we should always con‐ trast whatever failures we expect from individual choice with the predictable failures of government intervention.55 In fact, the di‐ chotomy between undirected individual choice and coercive govern‐ ment rules is misleading. Social norms are important sources of social order and can deeply affect our individual preferences. When	we	think	about	social	interactions	with	many	players	and multiple equilibria, norms and laws can be thought of as rival ways of moving	us	from	one	equilibrium	to	another	(socially	superior)	equi‐ librium. In small groups whose members have common values, low monitoring costs, and limited migration, collective action problems are typically best solved through informal norms. But in the kinds of collective action problems we're envisioning, millions of people in nation‐states and potentially billions of people around the world will be interacting in complex games that occur across time and space. In some cases, parents will move between different states or they will move between different communities within a state. The conditions for social norms to solve collective action problems will not always apply in these cases, unless people return to living in small and sta‐ ble communities where norms can more powerfully sculpt behavior, including reproductive preferences. This makes it hard to know what to do about far‐reaching col‐ lective action problems-for example, those that arise because many parents may prefer extraverts to introverts, or because all would prefer a population with more empathy, but each would pre‐ fer a child with less empathy than average. There is no algorithm that can tell us when we should rely on norms or laws to solve col‐ lective actions problems, though there are general rules of thumb that we can glean when we distinguish small number from large number cases, or cases with extensive externalities from those in which the consequences of our choices are mostly internalized.56 We	want to explore	what	Amy	Gutmann calls the principle of regulatory parsimony, which she coined as a response to the kinds of collective action problems that arise with genetic engineering in par‐ ticular, and synthetic biology more generally. Synthetic biology in‐ volves the use of computation and molecular biology to create and alter life.57 Some of the main uses include manipulating phage vi‐ ruses capable of replacing antibiotics to fight bacterial infections, creating gene drives to eradicate vectors for infectious diseases, res‐ urrecting extinct species, and altering the DNA of our children. According	to	Amy	Gutmann,	regulatory	parsimony	in	the	context	of synthetic biology recommends [O]nly as much oversight as is truly necessary to en‐ sure justice, fairness, security, and safety while pursu‐ ing	the	public	good.	Regulatory	parsimony	is	especially important in emerging technologies [...] where the temptation to stifle innovation on the basis of uncer‐ tainty and fear of the unknown is particularly great. The blunt instruments of statutory and regulatory re‐ straint may not only inhibit the distribution of new benefits, but can be counterproductive to security and safety by preventing researchers from developing effective safeguards.58 This is a vague principle. One way to clarify regulatory parsimony is to think of it as implying that when legislation is necessary to prevent serious harms that arise from coordination problems, we should aim for simple rules that apply to all. In the cases we have in mind we should avoid micromanaging parental choices that shape the traits of their chil‐ dren. There are a number of reasons to endorse this principle that are not discussed	by	Gutmann.	First,	complex laws are often harder for ordinary people and small firms to navigate than they are for powerful people and large corporations. Similarly, wealthy people can typically afford to travel great distances or pay high costs to obtain goods that black markets are likely to provide if demand is strong, and goods that are made either illegal or expensive due to complex or otherwise burdensome laws. Complex laws, then, can harm the smallest companies and most vulnerable people. Second, too many laws can crowd out social norms, which tend to be more sensitive to local conditions than government legislation.59 A small number of clear laws is less likely to stifle innovation. Innovation can occur both in the technology we seek to regulate but also in the norms and laws by which we might regulate the technol‐ ogy.	We	see	regulatory	parsimony	as	a	tacit	endorsement	of	federal‐ ism-the	idea	expressed	by	James	Madison	and	others	that,	although we occasionally need a few simple rules at the level of a national government or an international assembly, we should also ensure that we allow local communities to experiment with different ways of achieving the desired results. Third, laws can reduce liberty. The principle of regulatory parsi‐ mony in politics is analogous to the principle of the least restrictive alternative in ethics. Taking the least restrictive alternative is good because of the intrinsic value of liberty, but also because autonomy is promoted when people are confronted with alternatives and en‐ couraged to develop the ability to make difficult decisions rather than	relying	on	others	to	do	so	for	them.	Just	as	too	many	pharma‐ ceutical regulations can result in a kind of learned helplessness by consumers,60 an overly paternalistic approach to regulating genetic engineering can lead to false confidence in the wisdom of regulators and to a stunted capacity to make informed choices. Finally, political processes produce incentives that result in a non‐random set of people who end up as regulators. These people will tend to have their own parochial views about which traits matter most, and what composition of future people would be best. Some regulators may possess wisdom that those who they regulate lack. 55 Anomaly,	J.	(2015).	Public	goods	and	government	action.	Politics, Philosophy, & Economics, 14(2),	109–128. 56 Anomaly, J., & Brennan, G. (2014). Social norms, the invisible hand, and the law. University of Queensland Law Journal, 33(2),	263–283. 57 Venter,	C.	(2013).	Life at the speed of light: From the double helix to the dawn of digital life. New	York:	Penguin. 58 Gutmann,	A. (2011).	The	ethics	of synthetic	biology:	Guiding	principles for	emerging technologies. Hastings Center Report, 41(4),	17–22. 59 Ellickson,	R.	(1994).	Order without law. Cambridge, MA: Harvard University Press. 60 Flanigan,	J.	(2017).	Pharmaceutical freedom. Oxford: Oxford University Press. | 89ANOMALY et AL. But in many cases it will be the reverse and there are reasons to worry that giving regulators the power to micromanage procreative choices will leave some populations worse off than they would be with a greater degree of decentralized choice. What	would	regulatory	parsimony	recommend	for	dilemmas	like those discussed above? Choices that merely alter what some believe to be the optimal ratio of traits in the population should be permitted unless they produce a clear, uncompensated harm. Laws will be un‐ necessary if social norms evolve that reward people who have chil‐ dren with cognitive traits that are socially beneficial. Such norms could evolve because, as a population becomes skewed so that cer‐ tain cognitive styles are both beneficial and scarce, parents might be more inclined to select children with these properties-in part be‐ cause they will be rewarded with more successful lives due to the fact that their skills are in demand. This seems to be true for sex se‐ lection,	at	least	in	Western	countries,	where	the	ability	to	choose	a child's sex doesn't seem to have resulted in any major imbalance and has been mainly chosen for purposes of family balancing.61 More importantly, even if we can think of a hypothetical social optimum for a distribution of psychological traits and we agree on how to balance procreative beneficence and procreative altruism, it is not obvious that what experts come up with in estimating optimal‐ ity will be right or that people will listen to them. When	in	doubt,	we	should	defer	to	the	wishes	of	parents,	as	they typically have better incentives than regulators to figure out what traits will make their children flourish. As most parents would not maliciously produce children with traits that threaten the welfare of future people it may be superfluous to enact bans on selecting for anti‐social traits. But if parents refuse to take their responsibil‐ ities seriously by considering how their failure to select or alter an embryo	might produce easily preventable harms to their child (or the	future	people	whose	welfare	their	child	will	affect),	then	it	may be	worth	implementing	regulations	that	limit	these	choices.	We	do not think free choices will always produce an optimal distribution of traits, and we are skeptical that a specific optimum exists, given rea‐ sonable diversity in the relative weight that different people place on widely shared values. But even if we could agree on a socially op‐ timal distribution of traits we worry that states would be unlikely to achieve this optimum by micromanaging the procreative choices of parents.	When	legal	regulations	are	appropriate	to	prevent	serious harms we think they should be broad in scope and few in number. 7 | CONCLUSION Given	the	facts	of	scarcity	and	risk,	we	think	there	will	be	interesting trade‐offs when it comes to modifying genes associated with psy‐ chological	traits.	We	have	argued	that	as	different	traits	can	influ‐ ence individual happiness and collective prosperity we should pay attention to the kinds of choices that new gene‐editing techniques will make possible. In the short and medium term it is likely that choosing	a	partner	(or	sperm	and	egg	donor)	wisely	would	be	more effective and less risky than directly trying to edit genes to produce children with traits that are influenced by many genes interacting with each other. A lot of innovation in art and science depends on institutions,	not	(just)	genes.	But	to	the	extent	that	genes	influence who we are and what kinds of institutions we create there may be reasons to think about which social mechanisms we use for aggre‐ gating judgments, and which kinds of genetic enhancements might increase the welfare of each and the prosperity of all. ACKNOWLEDG MENTS Thanks	to	Jerry	Gaus	and	the	political	philosophy	workshop	at	the University of Arizona for helpful comments. CONFLIC T OF INTERE S T The authors declares no conflict of interest. ORCID Jonathan Anomaly https://orcid.org/0000‐0001‐5485‐0121 Christopher Gyngell https://orcid.org/0000‐0002‐1340‐3947 Julian Savulescu https://orcid.org/0000‐0003‐1691‐6403 How to cite this article:	Anomaly	J,	Gyngell	C,	Savulescu	J. Great	minds	think	different:	Preserving	cognitive	diversity	in an age of gene editing. Bioethics. 2020;34:81–89. https://doi. org/10.1111/bioe.12585 61 Savulescu, J.,	&	Dahl, E. (2000). Sex selection and	preimplantation diagnosis.	Human Reproduction, 15(9),	1879–1880. Jonathan Anomaly has helped build philosophy, politics, and economics	(PPE)	programs	at	Duke,	UNC,	Arizona,	Virginia, and	San	Diego.	He	is	a	visiting	scholar	at	the	Institute	for Practical	Ethics	at	UC,	San	Diego,	and	the	Uehiro	Centre	for Practical Ethics at Oxford University. Christopher Gyngell	is	a	Research	Fellow	in	Biomedical	Ethics at	the	Murdoch	Children's	Research	Institute,	Lecturer	in	the Department of Paediatrics at the	University of	Melbourne, and	a	Senior	Research	Fellow	at	the	Melbourne	Law	School. Chris has a background in genetics, corporate ethics and philosophy. Julian Savulescu is Uehiro Chair in Practical Ethics, University of Oxford. He directs the Oxford Uehiro Centre for Practical Ethics and co‐directs the	Wellcome Centre for Ethics and Humanities. He is Visiting Professorial Fellow in Biomedical Ethics at the Murdoch Children's Research Institute, Melbourne	and	Distinguished	International	Visiting	Professor in Law at the University of Melbourne.