When two men wish to raise a child together, they must either adopt (where neither of them will have a biological contribution) or use an egg donor and surrogate (where only one of them will make a biological contribution). In the future, that might not be the case. A new paper published in Cell describes the role of genetic regulators which influence whether an immature germ cell differentiates into a male or female cell, and how that process can be manipulated. In the future, it could even be possible for stem cells from a male to be used to produce an egg, allowing an infant to have two biological fathers.

Primordial germ cells (PGCs) are the stem cells that are able to give rise to either sperm or egg cells. The body typically uses hormonal signals and certain transcription factors in order to determine whether to make the male or female germ cells naturally. While SRY is the gene most widely known for its sex-determining function, the paper describes the importance of another SOX family gene, SOX17. As it turns out, SOX17 is another regulator of human PGC-like cells, and altering the gene can alter the fate of those cells. Rather than just building on our understanding of sex-determining processes, this could potentially have staggering implications for a number of families.

In the coming years, researchers may be able to manipulate this process and make it possible for two men to father a child without the need of an egg donor. This could occur by taking PGCs from one father, manipulating SOX17 and inducing those cells to become oocytes. Because the male has all of the relevant maternal information on his one copy of the X chromosome, the resulting egg cell would theoretically be fully functional. The second father would then need to provide a sperm sample with which to inseminate the egg, though a surrogate would be required to carry the baby throughout gestation.

Of course, there is a laundry-list of logistical and ethical concerns before this can become a reality. Primarily, human genetic modification to this degree is a huge gray area, with many against the idea of “designer babies” that would lead to a Gattaca-like society. This technique wouldn’t be employed to avoid potentially devastating diseases, such as the three-parent IVF which was recently approved in the United Kingdom. Thus, it could be harder to justify such drastic means solely for procreation.

While it is unfortunate, there is another barrier: Those with prejudices against homosexual couples could block the development and implementation of this technology. Though the number of children being raised by same sex couples has nearly doubled since 2000, they are still far and away a minority and face many prejudices.

There is still a great deal of research that needs to be done before the time comes to decide how or if the technique will be implemented.