I really think it has to do with hooks. Have you ever dangled a hook in front of a man? It takes a long time to get a bite. But dangle one in front of a woman and she'll most times take it right away. As a society woman are programmed to respond (ever notice I guy fretting over an unsupervised child? but any normal woman, even if it's not her child will keep one eye on that kid). Since moms and this includes stepmoms are more inclined to react, we get baited more often.
My step daughter disowned her mother first, then me her stepmom, and by default her Dad. My husband has moved on, doesn't even care to talk about it, while I lose sleep

. The ultimatum actually given was that if my husband divorces me, he can see her two daughters! They are 1 and 3 btw. What am I a serial killer?

, Of course not. I'm not even dangerous, kids love me. That is the problem.
my 2 cents, I may be wrong, but this is what I have observed