>>715092427
Trying to apply scientific logic to how Uma are born is a fruitless endeavour, because it's literally magic. If the uma world wants you to have an uma baby, it will be zapped into you. That's that. There's no 'chance' and there's no 'new soul' being made, all Uma's are just horses getting isekai'd from varying points in both our history and our future. Trying to think about the matter beyond this is going beyond what Cygames desired.
Tachyon tries to logic shit like this and it's exactly why she's insane. As she says herself, even the physiology of how an Uma's body produces so much power despite it's frame is something science can't explain.
Any complex question you have about this franchise can be put down to 'the world willed it'.