Here is an interesting issue to examine: what moral judgment would you make about the use of three parents to one child? This is not a science fantasy but a genuine question which could lead to a change in the law.
It concerns mitochondrial DNA (mtDNA). Both ova and semen carry mtDNA but, at conception, only the female version is passed on. So, unlike nuclear DNA, it is not altered with every new generation – but is inherited complete. The reproduction is so accurate that it can identify the remains, say, of close relatives. It is frequently used in forensic investigations.
Unfortunately mtDNA can get damaged – and a child inheriting damaged mtDNA can suffer from very major problems. In theory (and, in some non-humans, in practice) it is possible to take an egg from a mother with healthy mtDNA, remove her nuclear DNA and replace it with the DNA of the would-be mother. The egg would then be fertilised by the prospective father’s sperm.
Since mtDNA can pass identically from mother to child and so on, it cannot be regarded as personal in the sense that nuclear DNA is unique to an individual (or identical twin).
In looking at the moral questions raised, some considerations arise. Is this is a legitimate interference with the dignity of the natural process of conception? Is introducing a third progenitor into a process, which is normally confined to father and mother only, legitimate? And, if this methodology should be introduced, will it be a further step which will be used as a precedent for more questionable manipulation of the procreative process?
All these questions are important because they relate eventually to synthetic or artificial biology. Suppose that you want a substantial amount of spider silk thread. It’s not practical to use spiders, so you insert the thread-making gene into a goat which then makes spider thread, which can be extracted in quality from their milk. You could call it a goat-spider.
Last year, Craig Venter – a pioneer in genetic matters – succeeded in creating a living cell with the help of DNA constructed by a computer. And indeed you can purchase, at a high price, the building blocks of synthetic biology, and string them together as you wish.
The law controls such procedures when applied to human beings, and the triple parent approach described is banned. But currently the question of it being permitted in future is under discussion. So what comes next? The capacity to modify home sapiens radically is already possible theoretically, and will certainly come within practical reach – and maybe quicker that we think because digitising biological processes cuts many corners. But each step of the way there will be sensible arguments, often based on compassion, just like the need for healthy mtDNA. And the law will accommodate.
So should we stop right now? Is it possible to stop right now? If we do not stop right now at what stage of manipulated human biology will we stop?
There is a good account of the consultation on triple parents and mtDNA to be found at, http://www.nature.com/nature/journal/v481/n7382/full/481410a.html
will tell you about the damage done by faulty mitochondria.