An old Genghis Khan can actually spawn little half-Khans, so as retarded as those young Khans would be there's a biological imperative, but an old women can't.

Probably the origin right there, there's no hard cutoff date for men.

I'm sure there's some grandpas in the more Jerry Springer areas who have had kids at 60 with some young doe and the kid turned more okay than expected.