And he ate the fool hen that raised him, didn't he?
Sorry, Amos. I couldn't resist.

I used to tell the following story to a parents' group, Girl Scout leaders in training, etc.:

A man collected fleas from his dog and put them into a Mason jar. The lid had holes in it so they survived. But everytime a flea would try to jump out, he hit his head on the top. After multiple injuries, the fleas stopped jumping so high. They still hopped happily about but only so high.
One day, the lid was taken off. The fleas were free to jump out. But they didn't. Having learned that jumping too high only got them a rap in the head, they continued to jump only so high.
The same is true with children. Tell them: "You're a girl. You can't be an astronaut." Or You're black. You can't be a college professor." Or "You're stupid. You can't be a doctor." Hit them on the head often enough and they too will stop trying to jump too high. They will never know how high they can go. Nor will we.