I believe we'd care about others' kids once we're ok with ourselves. I've seen it amongst women (mums and grandmas, obviously), we tend to form a strong flock and every kid in that flock is protected. Also such tribe tends to suck in other kids, which might be almost harmful to the mum neglecting said child, on the other hand the main urge is benefiting the kid and could help the neglecting mum a lot. What a new discovery this is.

And we drag our men into this too, their resources.

Point is to have a flock of mums and you're good. Bitches go insane.