The ‘Chimera’ of Parenthood
| Published date | 01 May 2021 |
| Author | Brian Sloan |
| Date | 01 May 2021 |
| DOI | http://doi.org/10.1111/1468-2230.12602 |
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Modern Law Review
DOI:10.1111/1468-2230.12602
The ‘Chimera’ of Parenthood
Brian Sloan∗
In apparently the rst reported instance of a paternity test being ‘fooled’ by a ‘human chimera’,
a man ‘failed’ a paternity test because the genetic material in his saliva was shown to be dier-
ent from that in his sperm. Such a chimera has extra genes, here absorbed from a twin lost in
early pregnancy. The result was that the ’true’genetic father of the man’s son was the twin, who
had never been bor n. Chimeras present a challenge to legal systems, given the frequent empha-
sis on genetics in determining parenthood. This paper considers the phenomenon’s potential
implications for English law’s understanding of parenthood.It advocates the recognition of the
chimeric person as the ‘true’ legal father and suggests two methods through which this might be
accomplished, pointing out their broader consequences.The paper also explores English law’s
likely practical response to the situation of a potential chimera.
INTRODUCTION
In 2015,The Independent newspaper reported1the case of a man who had ‘f ailed’
a paternity test in the United States because (it eventually transpired) the genetic
material in his saliva was shown to be dierent from that in his sperm.2This was
said to be the rst reported instance of a paternity test being ‘fooled’ by what is
known as a ‘human chimera’. Such a chimera has extra genes, in this instance
apparently absorbed from a twin lost in early pregnancy. The result was that,
according to the tests, the ‘true’ genetic father of the child in question was the
man’s twin, who had never been born. The man and the child’s mother were
not in dispute as to paternity and parenthood on the facts of the case. Instances
of chimerism nevertheless potentially present a challenge to legal systems where
there is such a dispute (whether motivated by child support,inher itance rights
or involvement in upbringing), given their frequent emphasis on genetics in
determining parenthood.
∗Fellow in Law, Robinson College, Cambridge. An earlier version of this paper was presented at a
Cambridge Socio-Legal Group/Cambridge Reproduction seminar in May 2020.Subject to the usual
disclaimer,I am very grateful for the extremely helpful comments of attendees, Alison Young and the
anonymous reviewers,and for social media interactions with Findlay Stark and Graham King on this
topic.
1 S. Khan,‘“Human chimera”: Man fails paternity test because genes in his saliva are dierent to
those in sperm’ The Independent 24 October 2015 at https://www.independent.co.uk/news/
science/human-chimera-man- fails-pater nity-test-because- genes-in- his-saliva-are-dierent-
to-those-in- sperm-a6707466.html (all URLs were last accessed 28 August 2020).
2 See further K.M. Sheets et al, ‘A case of chimer ism-induced paternity confusion: what ART
practitioners can do to prevent future calamity for families’ (2018) 35 Journal of Assisted Repro-
duction and Genetics 345.
© 2020 The Author.The Modern Law Review © 2020 The Modern Law Review Limited.(2021) 84(3) MLR 503–531
The ‘Chimera’ of Parenthood
Having explored the phenomenon of chimerism with reference to relevant
scientic literature,this paper analyses the likely response of the law of England
and Wales to the situation of a potential chimera. The focus will be on situ-
ations where the putative father3is a possible chimeric person in the context
of a paternity dispute.4After discussing the general approach of English law to
determining legal parenthood, the paper analyses the specic implications of
chimerism for determining legal fatherhood. In doing so, the paper considers
what the phenomenon of the chimera might tell us about our understanding of
parenthood and the similarities and dierences between biological motherhood
and fatherhood respectively,situating chimerism within more wide-ranging dis-
cussions about the nature of parenthood. The paper will acknowledge the po-
tentially signicant implications of chimerism for debates about the appropriate
basis of legal parenthood (given the potentially multifaceted and fragmented na-
ture of parenthood as a concept) and the opportunity it provides to test English
law’s coherence on parenthood more generally.It will nevertheless advocate the
recognition of the chimeric person as the ‘true’ legal father in cases of ‘natural’
reproduction.It will recognise that this may require even ‘natural’fatherhood to
be under stood as more of a ‘process’ than is often realised,but also point out the
possible dangers of that argument and the potential advantages of an alternative
approach based on the chimera’s ‘ownership’of all the relevant genetic material.
Lastly, the paper will highlight the need for open-mindedness in genetic testing
in order to identify suspected chimerism in the rst place.
THE PHENOMENON OF THE ‘CHIMERA’
The r st recorded literar y reference to a ‘chimera’ (sometimes spelled ‘chi-
maera’) is in Homer’s Iliad,where the term is used to descr ibe a mythical crea-
ture that is part lion, part serpent and part goat.5In medical science, chimer ism
describes a phenomenon ‘where an individual carries more than one com-
plete genome’.6A ‘congenital’ chimera is ‘an individual who carries the cell
populations of dizygotic twins’,7a term usually used to describe fraternal or
non-identical twins who come from separate ova and are fertilised by separate
sperm.8Chimerism is believed to occur through the fusion of twins at the ear-
liest stage of embryo development, or from maternal-fetal exchanges dur ing
3 Where a parent who has not given birth,including a second female parent who is not a ‘father’,
acquires their status by virtue of adoption, surrogacy or compliance with the assisted reproduc-
tion provisions in the Human Fertilisation and Embryology Act 2008, chimerism will be less
relevant because that person need not have provided the sperm in any event.See fur ther n 41
below.
4 See for example K. Sheets and R. Wenk, ‘Relationship Testing and Forensics’ in N.L. Draper
(ed), Chimerism: A Clinical Guide (Cham: Springer, 2018) 58 on potential diculties where the
child is a suspected chimera.
5 E. Bazopoulou-Kyrkanidou,‘Chimer ic creatures in Greek mythology and reections in science’
(2001) 100 American Journal of Medical Genetics 66.
6 Sheets et al, n 2 above, 346.
7 Sheets and Wenk,n 4 above,51.
8 J.M Quinn, ‘Dizygotic twin’ in Encyc lopaedia Britannica (2013) at https://www.britannica.com/
science/dizygotic-twin.
504 © 2020 The Author.The Modern Law Review © 2020 The Modern Law Review Limited.
(2021) 84(3) MLR 503–531
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