‘Of Mice and Men’

The Second International Summit on Human Genome Editing in 2018 really hit the headlines when Prof He Janjkui announced he had carried out heritable genome editing of twin girls in China to make them more resistant to HIV infection. In contrast, the Third International Summit in London in early March 2023 got far less press coverage. The story which attracted the most interest was about mice.

A Japanese team announced they had successfully produced healthy mice pups from two fathers using a surrogate female mouse for gestation only and not as a source of eggs. Unsurprisingly this prompted speculation about male gay couples being able in the next ten years or so to have children genetically related to both men.

Interestingly, the same thing had already been attempted over five years ago and did enable the production of healthy pups from two mothers. However, in that experiment, the pups derived from two fathers died after only a few days. That advance five years ago got virtually no media attention. This time around, there was more coverage. But many press reports did not mention the need for a surrogate mother. Those that did flag it up also hoped that developments in ectogenesis would eventually render surrogate motherhood redundant. That way, should they so desire, two men could go it entirely ‘on their own’ for a child genetically related to both of them.

Many people were taken by surprise by the story. But ever since the discovery back in 2006 by Takahashi and Yamanaka that adult somatic cells could be induced in vitro to become stem cells, the door to the possibility of reproduction by same-sex couples (or even a single individual) has been opened. As such, induced pluripotent stem cells (iPSCs) are capable of developing into any type of adult cell, including gametes. It was, therefore, only a matter of time before offspring from parents of the same sex were produced in laboratory animals. Perhaps it will eventually be achievable in humans too. Most Western societies with the wealth to make this happen decided decades ago that same-sex parenting of children was socially and ethically acceptable, so generating children genetically related to both (or even more than two) same-sex parents is a logical next step. Though Scripture indicates that the knowledge to become immortal has been withheld from humanity (Genesis 3:22), the same cannot be said for same-sex reproduction.

Biologically, however, there are still many unknowns. The innovation that enabled the reproduction of healthy pups from two males in this breakthrough exploited the natural tendency of iPSCs in culture to spontaneously lose chromosomes, including the Y chromosome in cells from males. The scientists treated such cells with reversine, which promotes errors in chromosomal distribution during cell division. This then led to the presence of female cells, with two X chromosomes, which could be used to form egg cells which were fertilised with mouse sperm and implanted into surrogate mothers.

This resulted in seven pups being born from over 600 fertilised eggs. This low success rate illustrates the inefficiency of the procedure. Typically, dozens of healthy pups would be expected from over 600 conventional female eggs.

Many cures and other promises from previous overhyped ‘advances’, such as the creation of animal-human hybrids and mitochondrial donation techniques, have failed to materialise as yet (and probably never will in the case of mitochondrial donation). One of the major ethical issues with this latest announcement is the potential waste of millions of pounds on developing a technique that works in some non-human species but is not transferable to humans. If it proves transferable, Christians and all people of faith will need to recognise that same-sex parenting is nothing new. The day in 2008 that the HFEA succeeded in removing any regard for ‘the need of a father’ to obtain IVF paved the way for two mothers to parent and now, ironically, for two fathers as well.