It's well known that the Grimm brothers didn't do much to advance respect and reverence for stepmothers. Those bastards will forever be on my shit list for coining the "wicked/evil stepmother" phrase. Where's the disdain for the fathers who left their children in the care of these women and who let themselves be controlled so easily? But I digress.
There are several theories as to why fairy tales are filled with evil stepmothers. One is that it is more believable that a stepmother would be trying to off the kids than a mother. Maybe, but most stepmothers I know are just as horrified at the thought of hurting a child as are mothers. I have my own theory as to how fairytale stepmoms got such a bad reputation. These stories are told from the child's side. Did anyone ask Snow White's stepmother for her version of the events? Everyone knows kids are prone to exaggeration (I never knew until just now how to spell exaggeration. Two Gs. Who knew?) and even outright lying. Here's my theory on the origins of some well-known "wicked" stepmothers.

Cinderella- Poor Cinderella forced by her stepmother to do all the chores around the house while her daughters did nothing. I know this one too. My stepson has two chores when he is at our house, setting the table and making his bed, yet I can't tell you how frequently he bemoans having to do EVERYTHING around here. You see when Cinderella lived alone with her dad, things like eating at a table and basic sanitary conditions went out the window. Men do not see mess, so Cinderella's dad couldn't have told you if Cinderella even had sheets on her bed much less whether or not it was made. And dinner, he just wanted to eat it in front of the TV. Then in comes the horrible stepmother with her family dinners and hygiene requirements and suddenly Cinderella's life of sloth came to an end. And those ugly stepsisters, obviously when they weren't willing to put up with her attitude and complaining about all. those. chores., it was because they were jealous of her beauty. Too bad they didn't write a follow-up to Cinderella after she is married and has kids and then finds out what it really means to have to do everything around here.
Hansel and Gretel- Hansel and Gretel's single dad liked to do whatever kept his kids happy and out of his hair. If that meant playing with dwarf figures (or whatever the old time equivalent to video games would be) and eating junk 19 hours a day, so be it. When his new wife moved in she was appalled at H &G's pasty complexions and rotund figures. So she took it upon herself to make some changes. Some might say she was overstepping, but she really had their best interest at heart and quite frankly the family couldn't afford to keep buying all that junk food after the snack tax was instated. First she started making them eat vegetables, which really pissed H&G off. They were used to getting their way all the time with their dad. So they were none too amused when one sunny day, their stepmom had their dad make them go outside and not come back....for at least an hour. In desperate need of a candy fix, H&G went off to steal some candy from the old lady down the road, home invasion style. The joke was on them when the old lady turned the tables on them. By the time their dad found them, they had revised their story so that "they had been deserted and the old lady had candy on the outside of her house. We thought it was free and then she just went crazy on us."

OK. I got a little off topic in that last one, but those two German brats (ha ha) have always seemed a little shifty to me. And what about the mysterious death of their stepmother? Seems fishy to me.
So remember, next time you hear someone complaining about their evil stepmother, there are two side to every story. And one little brown spot won't kill you.