I'll never forget the conversation I once had with a guy responding to one of my articles. I don't even remember what I'd been writing about, but equal opportunity for children to play sports was part of it.

A man responded that, as a father, he could not agree with my notion, and that he'd never personally let his preteen daughter play baseball with boys.

I was a little confused by that, so I just asked him why.

"So she doesn't get hurt, duh!" he replied, not explaining beyond that.

I answered that 10 to 12-year-old girls are often bigger than 10 to 12-year-old boys, so I wondered what he was worried about. Why would his daughter be hurt playing with boys?

He answered that I was "out of your mind" and that I needed to do some parenting so I would understand. (I guess he just assumed that as a gay man I had never parented, although that is not true.)

But he was so socialized to believe that women/girls are physically weak, that he couldn't wrap his mind around the fact that nothing about pre-teen girls puts them in danger if they play games with boys who are the same size or smaller than they are.

And that socialization is widespread. Girls usually play softball if they play at all. Even though Little League Baseball is officially open to girls, it's quite rare to see a girl playing.

That isn't biology or the natural world dictating behavior. It's socialization. Socialization has convinced that dad that his daughter is too weak to play with boys, even though it isn't true.