Look at Disney

You need it.

I don't know if I'm gay or bi or anything, but I had a relationship once with another man, no sexual stuff just dating

Just by not doing anything actually, most boys will tell their parents that they fell in love with x girl and gave them flowers

It's mostly territorial

In nature you're supposed to, being able to is related to health problems. But yeah, I will raise my son/daughter in heterosexuality, if he/she wants to be gay/bi/etc that's fine. But I don't expect little boys to like other boys for example

Default because reproduction