Bioethics. 2019;00:1–6. | 1wileyonlinelibrary.com/journal/bioe 1 | INTRODUC TION Dolly the sheep is probably the most famous sheep in the world, and she is rightly so as she was the first mammal produced via cloning. In cloning the nucleus of a somatic cell is transferred into an enucleated oocyte (i.e. an oocyte whose nucleus has been previously removed), and then it is activated by external means. If everything goes accord‐ ing to plan the cell will begin to divide, the embryo will be transferred into a womb (under the appropriate biological conditions) and then, after some time, an 'nearly identical genetic copy' of the individual who provided the somatic cell (i.e. the nuclear DNA provider) will be born.1 I say a nearly identical genetic copy because whereas the to‐ tality of the nuclear DNA would come from the nuclear DNA pro‐ vider, the zygote's mitochondrial DNA would most certainly not come from said nuclear DNA provider, or the provider's maternal line. This is the case as in mammals mitochondria are matrilineally transmit‐ ted.2 For the clone to be an identical genetic copy, sensu stricto, of the nuclear DNA provider the latter, or someone from their maternal line, should also provide the would‐be enucleated egg that in turn contains the mitochondria. After the birth of Dolly scientists around the world started to try to clone other mammals, and up to this date cats, coyotes, camels, dogs, 1 Wilmut,	I.,	Beaujean,	N.,	de	Sousa,	P.	A.,	Dinnyes,	A.,	King,	T.	J.,	Paterson,	L.	A.	...	Young, L.	E.	(2002).	Somatic	cell	nuclear	transfer.	Nature, 419(6907), 583–587. 2 It	is	very	uncommon	for	paternal	mitochondria	to	be	incorporated	into	the	zygote.	Luo,	S., Valencia,	C.	A.,	Zhang,	J.,	Lee,	N.	C.,	Slone,	J.,	Gui,	B.,	...	Huang,	T.	(2018).	Biparental inheritance of mitochondrial DNA in humans. Proceedings of the National Academy of Sciences of the United States of America. 115(51),	13039–13044;	Schwartz,	M.,	&	Vissing,	J.	(2002). Paternal	inheritance	of	mitochondrial	DNA.	New England Journal of Medicine, 347(8), 576–580. Received:	8	December	2018 | Revised:	25	March	2019 | Accepted:	15	May	2019 DOI: 10.1111/bioe.12639 R E S P O N S E Genetic parenthood and causation: An objection to Douglas and Devolder's modified direct proportionate genetic descent account César Palacios‐González This	is	an	open	access	article	under	the	terms	of	the	Creat	ive	Commo	ns	Attri	bution	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 Oxford	Uehiro	Centre	for	Practical Ethics,	University	of	Oxford,	UK Correspondence César	Palacios‐González,	Suite	8,	Oxford Uehiro	Centre	for	Practical	Ethics, University	of	Oxford,	Littlegate	House, 16/17	St	Ebbe's	Street,	Oxford,	OX1	1PT,	UK Email:	cesar.palaciosgonzalez@philosophy. ox.ac.uk Funding information CP‐G	is	currently	funded	via	a	Wellcome Centre	Grant	(grant	no:	203132/Z/16/Z). Abstract In	a	recent	publication	Tom	Douglas	and	Katrien	Devolder	have	proposed	a	new	ac‐ count of genetic parenthood, building on the	work of	Heidi	Mertes.	Douglas and Devolder's account aims to solve, among other things, the question of who are the genetic parents of an individual created through somatic cell nuclear transfer (i.e. cloning): (a) the nuclear DNA provider or (b) the progenitors of the nuclear DNA pro‐ vider.	Such	a	question	cannot	be	answered	by	simply	appealing	to	the	folk	account	of genetic parenthood, according to which the genetic parents of an individual are those individuals who produced the egg and sperm, respectively, which fused to create the embryo. It cannot be so as in cloning there is no fertilization as such. In this article I critically examine Douglas and Devolder's new account of genetic parenthood and demonstrate that it is vulnerable to counterexamples that exploit the lack of a condi‐ tion specifying that genetic parents should cause a child's coming into existence. K E Y W O R D S assisted	reproduction,	cloning,	genetic	parenthood,	Heidi	Mertes,	in	vitro	reproduction, mitochondrial replacement therapy, reproduction, stem cell derived gametes 2 | PALACIOS‐GONZÁLEZ goats, horses, mice, monkeys, pigs, rabbits and rats have already been cloned. Furthermore, one consequence of Dolly's birth was that people got even more interested in the question of whether human beings could be cloned, and if so whether it would be morally permissible to do so.3	Broadly	speaking,	two	positions	emerged.	On	the	one	had	there	are those who argue that it would be immoral to clone human beings, and on the other hand there are those who argue that under certain circum‐ stances it would be morally permissible to do so. An example of the former	is	Leon	Kass:	'Mass‐scale	cloning	of	the	same	individual	makes the point vividly; but the violation of human equality, freedom, and dig‐ nity is present even in a single planned clone'.4 An example of the latter is	Carson	Strong,	who	argued	that	in	certain	circumstances	it	would	be ethical for infertile couples to resort to cloning, as a way of having kin that were genetically related to one of them.5 One issue that becomes patent when we reflect on the possibly of employing human cloning for 'reproductive purposes' is that clon‐ ing does not fit our folk conception of genetic parenthood. According to this folk conception, the person who provided the egg and the person who provided the sperm, which fused and created an em‐ bryo, are the genetic parents of the created embryo. Cloning is prob‐ lematic because in it no sperm and egg fuse, and thus the question of who are the genetic parents of any given clone arise: (a) the person who provided the nuclear DNA, or (b) the progenitors of the person who	provided	the	nuclear	DNA.	Interestingly,	Leon	Kass	noticed	that reproductive cloning complicated our traditional understanding of human reproduction: 'Asexual reproduction, which produces "sin‐ gle‐parent" offspring, is a radical departure from the natural human way, confounding all normal understandings of father, mother, sib‐ ling, grandparent, etc., and all moral relations tied thereto.'6 In	a	recent	publication	Tom	Douglas	and	Katrien	Devolder	have proposed a new account of genetic parenthood. Their account, which	builds	on	the	work	of	Heidi	Mertes,7 aims to solve the ques‐ tion of who are the genetic parents of an individual created through cloning. They defend the view that the progenitors of the nuclear DNA provider are the clone's genetic parents. In this article I criti‐ cally examine Douglas and Devolder's new account of genetic par‐ enthood. Firstly, I show that Douglas and Devolder draw an incorrect conclusion when they apply their new account of genetic parent‐ hood to answer the question of whether an egg donor is a genetic parent, in cases where the egg used in the reproductive procedure has been enucleated (e.g. maternal spindle transfer, cloning). Secondly,	I	demonstrate	their	account	is	vulnerable	to	counterexam‐ ples that exploit the absence of a condition specifying that genetic parents should cause the child's coming into existence. The article proceeds as follows. In the second section I briefly present and explain why previous accounts of genetic parenthood are flawed. In the third section I present Douglas and Devolder's new account of genetic parenthood and show that they draw the wrong conclusion when faced with cases where an egg has been enucleated for a reproductive purpose. In the fourth, and final, sec‐ tion I present a case that shows that their account of genetic parent‐ hood is found wanting. 2 | ACCOUNTS OF GENETIC REPRODUC TION In this section I review the accounts of genetic parenthood that Heidi	Mertes investigated in her article 'Gamete Derivation from Stem	Cells:	Revisiting	the	Concept	of	Genetic	Parenthood';	and	ex‐ plain	why	they	are	found	wanting.	I	begin	with	Mertes,	as	Douglas and Devolder do likewise. The first account that she presents can be named the informational account of genetic parenthood: [A] child is my genetic child when it has 50% of my DNA or when it has 23 of my chromosomes. This 50% over‐ lap of genetic material is, for example, what is looked into when performing a paternity or maternity test.8 There are several problems with this account, as it focuses on in‐ formation overlap. Foremost, under it my siblings would be my genetic parents and vice versa. This would be the case as I share 50% of the information contained in my genetic nuclear material with my siblings. Furthermore, it can also be the case that I share 50% of my nuclear DNA, in the informational sense, with someone who is not a close relative of mine, and that would entail that she is my genetic child or parent. A	more	promising account,	which	Mertes	discusses and	which was first presented by Avery Kolers,9 can be named the Direct Derivation	Account	of	genetic	parenthood:	'X	is	a	genetic	child	of	Y if	X	is	directly	derived	from	Y's	genes'.10 The direct derivation condition rules out the possibility of my sib‐ lings being my genetic parents, as I was not directly derived from them,	and	vice	versa.	As	Kolers	asserts:	'[d]erivation	is	fundamentally a causal relationship; the offspring is as it is because of its relationship to its parents, whereas the inverse is not true'.11	Mertes	contends	that the problem with this account is that it leads to counterintuitive con‐ clusions when we examine two reproductive cloning cases.12	Let	us, following Douglas and Devolder, call the first case the Cloned Child: 3 Devolder,	K.	(2017).	Cloning.	In	Zalta,	E.	N.	(Ed.).	The Stanford encyclopedia of philosophy. Stanford,	CA:	Stanford	University.	https	://plato.stanf	ord.edu/entri	es/cloni	ng/ 4 Kass,	L.	R.	(1998).	The	wisdom	of	repugnance:	Why	we	should	ban	the	cloning	of humans. Valparaiso University Law Review, 32(2), 697. 5 Strong,	C.	(1998).	Cloning	and	infertility.	Cambridge Quarterly of Healthcare Ethics, 7(3), 279–293. 6 Kass,	op.	cit.,	note	4,	p.	690. 7 Mertes,	H.	(2014).	Gamete	derivation	from	stem	cells:	Revisiting	the	concept	of	genetic parenthood. Journal of Medical Ethics, 40(11), 744–447. 8 Ibid,	p.	744. 9 Kolers,	A.	(2003).	Cloning	and	genetic	parenthood.	Cambridge Quarterly of Healthcare Ethics, 12(4), 401–410. 10 Mertes,	op.	cit.,	note	7,	p.	744. 11 Kolers,	op.	cit.,	note	9,	p.	402. 12 In	what	follows	I	will	bracket	the	question	whether	the	egg	donor,	for	the	cloning procedure, is a genetic parent under the Direct Derivation Account. I do so as I will expand on this issue later on. | 3PALACIOS‐GONZÁLEZ [A] couple (Mr and Mrs X) may become infertile after already having conceived one genetically re‐ lated	child	(Y).	As	they	long	for	a	second	child,	they opt to	clone their	existing	child	Y,	which results in the birth of Z.13 According	to	the	Direct	Derivation	Account,	Mr	and	Mrs	X	are not the genetic parents of Z. They are not so as Z was not directly derived	from	their	genes.	On	the	other	hand,	Y	is the genetic par‐ ent	of	Z,	as	Z	was	directly	derived	from	Y's	genes.	Nevertheless, according	to	Mertes,	in	this	scenario	'it	is	most	likely	that	Mr	and Mrs	X	will	"feel"	like	the	genetic	parents	of	Z,	whereas	Y	is	unlikely to	think	of	herself	as	Z's	mother.'	Let	us	now	consider	the	second case	that	Mertes	presents,	that	I	will	call	Cloned	Parent,	also	fol‐ lowing	Douglas	and	Devolder:	'Mr	and	Mrs	X	decide	to	clone	Mr	X instead	of	Y,	resulting	in	child	Q.'14 According	to	the	Direct	Derivation	Account,	Mr	X	is	the	only ge‐ netic	parent	of	Q.	He	is	so	as	Q's	genes	were	directly	derived	only from	Mr	X.	Now,	Mertes	notices that in this	case the nuclear DNA provider and the clone do not share 50% of DNA, but 100%. The people who would	pass [in	Cloned	Parent]	a	maternity/paternity test	would	be	the	genetic	parents	of	Mr	X.	In	this	sec‐ ond	scenario,	both	Mr	X	and	his	parents	might	con‐ sider themselves as Q's genetic parents and both would have good arguments (either a contribution of 50% DNA or direct derivation) to support their claim.15 The overall issue here, according to	Mertes, is that	we have contradictory intuitions on similar cloning scenarios. On the one hand, in Cloned Child we seem to support the idea that the pro‐ genitors of the nuclear DNA provider are the genetic parents of the clone.	But	on	the	other	hand,	in	Cloned	Parent	we	seem	to	support the idea that the nuclear DNA provider is the genetic parent of the clone. Of course, holding both statements as true at the same time is contradictory. After	presenting	these	two	cloning	cases	Mertes	does	not	bite the	bullet	and	accept	that, in	Cloned	Child,	Z's	genetic	parent is	Y. And she also does not try to revise the Direct Derivation Account in order	to	solve	this	purported	contradiction in	our intuitions.	What she does is assert that these two cases show that '[t]here is no fixed, scientific, everlasting criterion of genetic parenthood that everyone can agree upon' and that 'the term genetic parenthood is not value‐ free, but dependent on personal intuitions, intentions or judge‐ ments'.16 Let us now	move to	Douglas and	Devolder's account of genetic parenthood. 3 | THE MODIFIED DIREC T PROPORTIONATE GENETIC DESCENT ACCOUNT Douglas	and	Devolder	contend	that	Mertes's	conclusion	about	ge‐ netic parenthood is premature, in the sense that she has not shown that genetic parenthood is 'a subjective concept that depends on the views of people about what sorts of genetic relation matter'.17 Rather than falling for this subjectivist account of genetic parent‐ hood they propose a new account, one that can deal with the Cloned Child	and	the	Cloned	Parent	cases.	But	importantly,	their	account	is intended to be one 'that captures the concept of genetic parent‐ hood implicit in everyday usage'.18 Before engaging	with	Douglas and Devolder's account, it is important to notice that they do not start	from	Mertes's	presentation	of	the	Direct	Derivation	Account, but rather from a revised	version	of	it:	'Direct	Genetic	Descent:	P	is C's	genetic	parent	if	and	only	if	(a)	C's	genes	derived	from	P's	genes, and (b) not through deriving from the genes of some third, interven‐ ing	individual,	M.'19 They start from this revised version in order to avoid a possible counterexample: Suppose	a	sperm	from	P1 is	used	to	fertilize	an	egg from	P2.	The resulting zygote then	has its	DNA re‐ moved and replaced by DNA from some other individ‐ ual T. This zygote is then carried to term and eventually a child, C, is born. There is a sense in which C derives directly from P1 and P2's genes; those genes gov‐ erned the development of gametes, which created a zygote	from	which	C	developed.	But	C's	genes	do	not derive from	P1 and P2's genes, they derive instead from	T's genes, and this surely prevents P1 and P2 from qualifying as C's genetic parents.20 Douglas	and	Devolder's	Direct	Genetic	Descent,	which	is	a	revised version of	Mertes's presentation of the Direct Derivation Account, runs into the same issues mentioned above when we consider the Cloned	Parent	and	Cloned	Child	cases.	Now,	Douglas	and	Devolder offer	a	refined	version	of	Direct	Genetic	Descent,	which	seems	to	an‐ swer the question of who are the clone's genetic parents, while at the same time maintaining the concept of genetic parenthood implicit in everyday usage: Direct	Gametic	Genetic	Descent:	P	is	C's	genetic	par‐ ent	if	and	only	if	(a)	C's	genes	derived	from	P's	genes, (b) through a gamete produced by P, and (c) not 13 Mertes,	op.	cit.,	note	7,	p.	745. 14 Ibid. 15 Ibid. 16 Ibid. 17 Douglas,	T.,	&	Devolder,	K.	(2018).	A	conception	of	genetic	parenthood.	Bioethics, 33(1), 54–59, p. 4. 18 Ibid,	p.	1. 19 Ibid,	p.	3. 20 Ibid. 4 | PALACIOS‐GONZÁLEZ through deriving from the genes of some third, inter‐ vening	individual,	M.21 Douglas and Devolder here introduce the condition that the ge‐ netic derivation must be via a gamete produced by the intending ge‐ netic parent. Thus it follows from this account that the nuclear DNA provider, in cloning cases where the enucleated egg does not come from said nuclear DNA provider, is not a genetic parent of the clone. In such cases he or she is not a genetic parent as the clone was not derived from	one	of their gametes. In	Cloned	Child,	Y,	who is the nuclear DNA provider, is not the genetic parent of clone Z. And in Cloned	Parent,	Mr	X,	who is the	nuclear	DNA	provider, is	not the genetic	parent	of	Q. Douglas and Devolder also conclude, following the Direct Gametic	Genetic	Descent	account,	that	in	cases	where	we	employ	a mitochondrial replacement technique the egg donor is not a genetic parent	of the created child.	Direct	Gametic	Genetic	Descent 'also allows	us	to	evade	the	conclusion	that	P3	(the	mitochondrial	donor) is the genetic parent of C4 (the mitochondrial recipient) in Mitochondrial	Donation.'22	Let	us	remember	that,	broadly	speaking, mitochondrial replacement techniques are those where the nuclear DNA of the intending mother (or intending parents) is transferred from an egg (or zygote) with deleterious mitochondrial DNA muta‐ tions, to an enucleated egg (or zygote) that possesses healthy mito‐ chondria.23 It is also relevant to bear in mind that mitochondrial DNA corresponds to, roughly, 0.1% of the whole DNA content of the human organism. Douglas and Devolder are mistaken in their application of Direct Gametic	Genetic	Descent	to	mitochondrial	replacement	techniques cases. In such an account the egg donor for a mitochondrial replace‐ ment technique is a genetic parent.	Why?	Because	the	child's	mito‐ chondrial genes were derived from the egg donor's genes (Douglas and Devolder does not specify if there is a minimum of genes that must be transmitted for someone to classify as a genetic parent), from a gamete produced by the egg donor, and not by deriving such genes from the mitochondrial genes of some third, intervening indi‐ vidual,	M.	And	the	same	rationale	would	apply	to	the	egg	donor	in cases of reproductive cloning: she would be a genetic parent of the clone, regardless of the fact if she is also the nuclear DNA provider. Now, Douglas and Devolder assert that from Direct Gametic Genetic	Descent	it	follows	that	neither	of	the	clones	(i.e.	Q	and	Z) has	genetic	parents:	Direct	Gametic	Genetic	Descent 'implies that the	clones	created	in	Cloned	Child	and	Cloned	Parent	lack	any	ge‐ netic parents, since their genomes were not inherited via gametes'.24 Stricto sensu Douglas and Devolder are incorrect. The clones created in	Cloned	Child	and	Cloned	Parent	have	at	least	one	genetic	parent: the egg donor. Bracketing	the	previous	issue	regarding	egg	donors,	Douglas	and Devolder	assert	that	Direct	Gametic	Genetic	Descent	is	not	only	prob‐ lematic because the clones would not have genetic parents, which they	do.	They	contend	that	Direct	Gametic	Genetic	Descent	is	flawed because there are other cases that are 'closer to those of normal human reproduction' that also create problems for such an account. As a point in case, imagine that the following is possible: we enucleate a zygote, and we replace its nuclear material with the genetic material obtained	from	two	somatic	cells	taken	from	individuals	A	and	B.	In	this case each individual contributes 50% of the nuclear DNA material.25 If this were ever to happen then, under direct gametic genetic descent, we would have to accept that any resulting child from this biotechnol‐ ogy,	let	us	call	it	(following	Douglas	and	Devolder)	Two‐Donor	Genome Transplantation,	would	not	have	genetic	parents.	Yet	it	seems	that	in this	case	A	and	B	would	be	the	genetic	parents. In order to solve the problem posed by Two‐Donor Genome Transplantation, Douglas and Devolder propose to replace the con‐ dition of genetic inheritance via gametes with a condition of genetic inheritance of some determined proportion from parent to child. They	call	their	new	account	Direct	Proportionate	Genetic	Descent: P	is	C's	genetic	parent	if	and	only	if	(a)	some	propor‐ tion	X	of	C's	genes	derived	from	P's	genes	and	(b)	not through deriving from the genes of some third, inter‐ vening	individual,	M.26 If	proportion	X,	which	they	do	not	specify,	were	to	be	<100%	of the nuclear DNA, then under this account the nuclear DNA provider is not	the	clone's	genetic	parent.	And	if	proportion	X	were	to	be	>	0.1%	of the whole DNA then the egg donor, in cases where we employ maternal spindle transfer, for example, would not be a genetic parent. Now, the upshot	of the	Direct	Proportionate	Genetic	Descent	account is that it	does	not	entail the	absurd	conclusion	that in	Two‐Donor	Genome Transplantation the resulting child has no genetic parents. According to this	account	A	and	B	would	be	the	child's	genetic	parents.	This	would be the case if the proportion of genetic material established by this account	(i.e.	X)	is	set	to	include	the	proportion	that	obtains	in	cases	of sexual reproduction. Even	though	Direct	Proportionate	Genetic	Descent	can	accom‐ modate certain counterexamples, Douglas and Devolder maintain that	according	to	it	the	clones	created	in	Cloned	Parent	and	Cloned Child still do not have genetic parents: However,	Direct	Proportionate	Genetic	Descent re‐ mains too stringent in the cases of Cloned Child and Cloned Parent, for it continues to imply that the clones produced in these cases have no genetic par‐ ents	– an implication that	Mertes and	Sparrow find implausible.27 21 Ibid,	p.	4. 22 Ibid. 23 Palacios‐González,	C.	(2017).	Ethics	of	mitochondrial	replacement	techniques:	A Habermasian	perspective.	Bioethics. 31(1), 27–36. 24 Douglas	&	Devolder,	op.	cit.,	note	17,	p.	5. 25 Ibid. 26 Ibid. 27 Ibid. | 5PALACIOS‐GONZÁLEZ It is important to note that this conclusion does not necessarily follow	from	their	account. It	does	not	do	so	as	proportion	X	could be a proportion of genetic material in the range between 50% and 100%. The fact that the nuclear DNA provider passes 'too much' of her genetic material does not rule her out from being a genetic parent in principle. Regardless of how we solve the previous point, under	Direct	Proportionate	Genetic	Descent	the	genetic parents of the	nuclear	DNA	provider	(i.e.	the	parents	of	Mr	X	and	Y)	cannot	be regarded	as	the	genetic	parents	of	the	clone	(i.e.	Q	and	Z);	as	in	such cases they – the genetic parents of the nuclear DNA provider – are the 'third intervening individual'. Douglas and Devolder contend that it is possible to revisit the conditions	established	in	Direct	Proportionate	Genetic	Descent	and soften them, so we arrive at an account of genetic parenthood that does	not	conclude	that	in	Cloned	Parent	and	Cloned	Child	the	clones do not have genetic parents. In the previous paragraph I have shown that this 'softening' is not necessary, but adopting such solution would entail abandoning the concept of human genetic parenthood implicit in everyday usage. The way in which Douglas and Devolder weaken	Direct	Proportionate	Genetic	Descent	is	by	abandoning the idea that there cannot be a third intervening individual. Now they accept that in some instances there can be a third individual involved in	the	reproductive	endeavour.	But,	interestingly,	this	third	individ‐ ual is not a genetic parent, but what can be described as a bridge be‐ tween progenitors and descendants. For example, in Cloned Child case they 'propose that the intervening individual (C1) does not break the genetic parenthood relation	[between	P1	and	P2,	and	C2]	in	this case because she passes on too much of her genetic information to C2 [emphasis added]'.28 Douglas and Devolder formalize their re‐ vised account as follows: Modified Direct Proportionate Genetic Descent:	P	is	C's genetic parent if and only if (a) some proportion	X	of C's	genes	derived	from	P's	genes	and	(b)	not	through deriving from the genes of some third, intervening in‐ dividual M from whom C derived proportion Y of his genes.29 Douglas and Devolder accept that 'the proportion of genes' will most probably not be a set figure but rather a range, and that this range	could	have	fuzzy	boundaries.	Before	I	show	why	this	account of genetic parenthood is found wanting, it is relevant to mention that according to it egg donors, both for cloning and mitochondrial re‐ placement procedures, are not in principle ruled out as genetic par‐ ents.	Why?	Because,	as	stated	above,	the	authors	do	not	specify	the proportion of genes that must be transmitted for someone to clas‐ sify	as	a	genetic	parent.	If	the	proportion	were	≥	0.1%	of	the	whole DNA content of the human organism then the egg donor would be the genetic parent of the resulting child. This would be so as the mi‐ tochondrial genes of any resulting child would have been derived from the egg donor's genes, and not at all through some third inter‐ vening	individual	M.30 4 | THE C A SE AGAINST THE MODIFIED DIREC T PROPORTIONATE GENETIC DESCENT ACCOUNT Even	if	Douglas	and	Devolder's	account	avoids	what	they	consider	to be	a	counterintuitive	conclusion	(i.e.	that	Mr	X	is	Q's	genetic	parent, and	that	Y	is	Z's	genetic	parent),	they	run	into	a	more	severe	problem for not having a causation condition built into their account. In order to appreciate this issue consider the following case, which I will call 'Genome	Editing	'.	Alfred	and	Betty	want	to	have	a	child.	They	have been unsuccessful in achieving their goal through sexual intercourse, as both of Betty's fallopian tubes are completely blocked. Alfred and Betty decide to resort to Charles, a fertility expert. Charles prescribes Betty some fertility drugs and then proceeds to surgi‐ cally retrieve her eggs. Once the eggs have been retrieved he uses Alfred's sperm in order to carry out in vitro fertilization, and zygote E	is	produced.	After	the	IVF	procedure	Charles	does	not	transfer	the zygote	back	to	Betty,	but	rather	he	lets	it	grow	in	his	lab	for	3	days. On	the	fourth	day	Charles	uses	a	Genome	Editing	technique	in	order to	modify	E's	cells. In this	case	he inserts	10%	of	his	own	nuclear genes into	E's	cells.	Finally,	Charles	transfers	the	genetically	modi‐ fied	embryo	to	Betty,	and	after	some	months	E	is	born. According to Modified Direct Proportionate Genetic Descent both	Alfred	and	Betty	are	E's	genetic	parents,	if	'proportion	X'	is	set to include a range between 5% and 50% of the total nuclear ma‐ terial. They are so in that 45% of E's nuclear genes	were derived from each one of them, and not through deriving from the genes of some third intervening individual. The question to answer now is whether	Charle,	the	fertility	doctor,	is	E's	genetic	parent.	When	E	is first created Charles is not his genetic parent, as he does not satisfy condition	(a).	But,	Charles	becomes E's genetic parent per means of a Genome	Editing	technology	when	E	is	4	days	old. This is the case as 10%	of	E's	genes	were	derived	from	Charles'	genes,	and	not	through deriving them from the genes of some third intervening individual. The fact that Charles becomes E's genetic parent shows that there is something wrong with Modified Direct Proportionate Genetic	Descent.	The	problem	is	that	this	account	allows	for	an	adult to become the genetic parent of an already existing individual; and this cuts against one of the necessary conditions of genetic parenthood: that one is one of the material causes of an individual coming into existence. Adopting a stance that maintains that such a causation condition is not necessary entails a radical revisionism of the con‐ cept of genetic parenthood, a revisionist position that needs to be defended. At this point someone could present two objections to my Genome	Editing	case.	First, they	could	argue that	given	that	early embryos can twin they are not individuals, in the sense of being 28 Ibid. 29 Ibid. 30 I	thank	an	anonymous	reviewer	for	bringing	this	point	to	my	attention. 6 | PALACIOS‐GONZÁLEZ unified biological organisms, and thus Genome Editing does not show that such an account is found wanting.31 There are three ways in which I can address this objection. Firstly, I could show that early embryos are in fact individuals, but I do not have enough space to defend	such	a	view	(see	Mathew	Liao	(2010)	for	a	defence	of	such position).32 Secondly,	my case could just be recast as referring to embryos that have passed the point where twining is possible. Third, Genome	Editing	works	in	non‐embryonic	cases	as	well.	Imagine	that rather than being a 3‐day old embryo, E is a 1‐year old baby. If Charles	were	to	edit	his	genome,	at	that	point,	so	that	now	10%	of	E's genome	derived	from	Charles	then	Charles,	again,	would	become	E's genetic parent, but this is absurd. The	second	objection	holds	that	in	Genome	Editing	it	is	not	the case that Charles becomes the genetic parent of an already existing individual, this is	not	so	because	replacing	10%	of	E's	genes	would destroy	E	and	create	a	new	individual	F.33	In	other	words,	E's	numer‐ ical identity would not survive the extent of such procedure. If this were so then Charles would be the genetic parent of the recently cre‐ ated individual F, in as much as 10% of F's genes derived from Charles' genes and not through deriving them from some third intervening individual. According to this objection Genome Editing does not even get off the ground. In order to respond to this objection the first thing I need to do is provide	an	account	of	what	an	organism	is.	According	to	Liao,	a	being X	is	essentially	an	organism	if a)	X	begins	to	exist	when	the	capacity	to	regulate	and coordinate metabolic and other life processes is there; b)	X	persists as long	as there is	what	may	be	called 'organismic continuity,' which is the continuing ability to regulate and coordinate metabolic and other life processes;	and	c)	X	ceases	to	exist	when	the	capacity to regulate and coordinate metabolic and other life processes is permanently gone.34 Now, it could be the case that all our DNA is necessarily required for the capacity to regulate and coordinate metabolic and life pro‐ cesses to be there; and thus, if some of it were to be replaced by similar DNA, but from a different origin, then the original capacity to regulate and coordinate would be destroyed and a new capacity would	be	created.	Even	when	it	is	intuitively	appealing	the	former	is incorrect. According to recent research 75% of our DNA is non‐cod‐ ing DNA.35	This	means	that	Charles	could	edit	10%	of	E's	non‐coding DNA, and this would not affect E's capacity to regulate and coordinate	metabolic	and	life	processes	thus,	also,	not	affecting	E's numerical identity. Furthermore, my response to this second objec‐ tion holds true even if it were to be the case that the findings of the Encyclopedia	of	DNA	Elements	project,	which	were	able	to	assign biochemical functions to 80% of the genome, were true.36	Let	me finish by saying that Genome Editing shows that Douglas and Devolder's	Modified	Direct	Proportionate	Genetic	Descent	account of genetic parenthood is presently found wanting, and that they need to do more work in order for it to be a plausible account of ge‐ netic parenthood. ACKNOWLEDG EMENTS I am grateful to the	Wellcome Trust for supporting this research (grant no: 203132/Z/16/Z). I also owe many thanks to Katrien Devolder,	Thomas	Douglas,	Giulia	Cavaliere,	Gabriel	De	Marco,	the editors of the journal and to the anonymous peer reviewers for their very valuable comments and suggestions on an earlier version of this paper. ORCID César Palacios‐González https://orcid. org/0000‐0002‐3825‐5311 AUTHOR BIOG R APHY Dr César Palacios‐González is a Career Development Fellow in Practical	Ethics	at	the	Oxford	Uehiro	Centre	for	Practical	Ethics. His	research	interests	include	bioethics,	philosophy	of	medicine, neuroethics	and	applied	philosophy.	He	is	part	of	the	team	run‐ ning	the	new	Masters	programme	in	Practical	Ethics	offered	by the	Oxford	Uehiro	Centre	for	Practical	Ethics in the	Faculty	of Philosophy	and	the	Department	for	Continuing	Education. How to cite this article:	Palacios‐González	C.	Genetic parenthood and causation: An objection to Douglas and Devolder's modified direct proportionate genetic descent account. 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