Why is it that stepdads can sometimes be great but stepmothers are almost always horrendous?
Mothers are often vicious to their
own children depending on how delivery went. Good fucking luck convincing them to give a rat's ass about some
other woman's kids. Only men can genuinely care for (and about) offspring regardless of lineage, because caring for a child is the only way a man can genuinely bond with one. Women bond first and foremost with their children through childbirth and nursing (take special note we've done all we can as a society to minimize/eliminate that bonding via pain killers, surgical intervention, breast pumps and artificial formula).
Bottom line is men are the world builders and understand how to care for living beings "in their sphere" by strengthening the familial bond. But as for women, if you didn't fall out of her and suckle milk from her breast as an infant,
fuck you, worm, she's only in it to catch the man, and
you're potentially in her way.
ETA: lest I sound like a MGTOW, this doesn't just happen in humans. It happens with other animals too. I adopted a cat from a neighbor a couple years ago, who told me the cat was a boy. Said cat was a girl, and pregnant with three kittens (surprise!). I'm fortunate enough to be in a position to care for them all anyway, so I kept her (and cared for her), helped her get ready for the Big Day (with my vet's help), and then helped care for the three wonderful kittens she gave birth to a month later.
For six months, she was a fantastic mother to her kittens (all boys). They were inseparable. She groomed them, fed them, protected them, taught them, etc.
At
exactly the six month mark, she turned on those poor little bastards like you wouldn't believe. Hissed at them, slapped them away if they approached or followed, growled any time she could see them, you name it. Naturally they had no fucking clue why (they were -- and are -- very healthy, friendly and well-behaved) and you could see it confuse them. Hell, it made them snuggle with
me more.
I asked my vet at their six-month checkup about it, and she laughed and said "oh, uh, yeah that's her 'get them out of the nest' instinct -- there's no spaying/neutering in the wild, so once they're mature enough to mate the mother chases them off her territory so they won't try to make more babies with her, for obvious reasons."
They're two years old now and that whole dynamic settled down (they never tried to hump the poor girl, and she's mellowed, though she still doesn't do more than "tolerate" their presence even now).
I'm told if the tom (i.e. father) had stuck around, he'd have cared for the kittens indefinitely, even into adulthood, taking them hunting, defending turf together, etc., but obviously tomcats are rarely in the picture in captivity.
Point being -- females are dicks to kids, even their own. Males are better parents in a lot of ways.