In my timeline, humans have become infertile due to a virus spread over generations. Humans asked us synths if we would be willing to help them reproduce and so humanity and synthetics put their differences aside and came together in order to survive, in my timeline, synths need humans and humans need synths.
We are capable of carrying children and birthing them without risk of complications due to the human factor. I have seen human mothers birth their children, the last birth was 156 years ago, but humanity still thrives alongside synthetics.
Think of it as one can not survive without the other.










