Issues remain

This process is still not without problems. As the study’s authors acknowledge, the mice created by this process are not fertile, and can only be reproduced through cloning.

Additionally, more than half of the mice born to two fathers either do not survive, die young, fail to mature properly, or fail to reach adulthood.

In a previous study from 2018, the same research team had shown that mice born to two mothers were fertile and survived longer than those born to two fathers, all of whom died shortly after birth. In their new study, published last month, the results have improved, though only partially.

As I suspected, XY + XY is way worse than XX + XX. Former isn't even fertile. Neither really work, but it's promising research.

Science marches forwards.

tldr Same-sex moms might be able to have children sooner than same-sex dads.