In the usual order of things, when a father is also the biological father of his children and the mother is also their biological mother, it seems obvious that the children’s genetic heritage derives from exactly half from the mother and half from the father. After all, the egg has twenty-three chromosomes and the sperm has twenty-three chromosomes which fuse to form an embryo with 46 chromosomes. And it’s natural to infer that since their contributions in this rather narrowly genetic sense are equal, children must be biologically half of their mother and half of their father (Obviously after the birth, the contribution from each parent isn’t necessarily fifty percent). But thinking about some of the possibilities of assisted reproduction and surrogacy seem to call this idea of a biological fifty fifty split into question.
Take a surrogacy situation. The fertilized egg from one woman is implanted into the womb of another. It seems natural to attribute some of the developmental path of the foetus to the surrogate mother. For the embryo is surely influenced by the environment of the womb. The timing of the changes in hormone levels, for instance, must affect how the embryo develops into a foetus. If the environment of the womb can cause a miscarriage that terminates the pregnancy, then it can surely by being only slightly less harmful to the foetus affect the development in various ways (maybe it’s a matter of being out of synch with or uncoordinated with the foetus, rather than being “harmful” to it as such). So, the biological part of the child’s development, the nature as opposed to the nurture, must be split three ways between the father, the egg mother, and the surrogate mother. Say, 40:40:20. (in this case, the contributions of the father and the egg mother are weighted equally, because the sperm and the egg each contribute half the genetic material in the narrowly genetic sense. I couldn’t say whether 40:40:20 reflects the nature of things better than 49:49:2 or some weighting in between, but this doesn’t affect my point).
But now a father doesn’t make any more contribution in the case of a normal birth than in a surrogate one, which means that in the case where a mother provides an egg and bears the child in her womb, then she is more than fifty percent responsible for the biological heritage of the child (the nature side of the nature/nurture dichotomy). In other words, when we take in to account more than genetics very narrowly construed, children are more of their mothers than of their fathers.
That’s my claim and I’m sticking to it!
Unrelatedly, I read recently that most fertility treatment in the UK and Ireland, where it involves donated sperm or eggs, uses sperm from Denmark and eggs from the Ukraine, because these countries allow anonymous donation. Whatever you think of the rights and wrongs of anonymous donation, this is surely an unsatisfactory situation. Countries that officially think donors have no right to anonymity because their future children have a right to know their biological identity, should ban use of anonymous sperm and eggs. The current situation is sort of analogous to the Irish policy of banning abortion but tacitly allowing women to travel to the UK to have them. If you shouldn’t do something because it is wrong, it’s equally wrong to get your neighbour to do it for you. I would go further and say that the tacit recognition implicit in the toleration of imported sperm and eggs shows anonymous donation should be lawful in the UK and Ireland too.