There's something called emotional incest. It's when a parent uses the child to get their needs met. As a young adult, I felt my mother was trying to seduce me. It might have been one of the ways she'd found with others to get attention, but it was extremely creepy. Mind you, she'd never touched me growing up.

Also, if one's father is absent or preoccupied, it's difficult to grow into a sexually complete adult. You don't feel like your father's there to protect you from your mother, so you repress your sexuality.

Finally, for me, it was a matter of not being allowed to be angry. My mother treated anger like it was a mental illness...of course it was ok for her to be angry. And anger is the way we protect our boundaries. So if our parents don't let us grow up and they have the power to anesthetize us, it's really hard to leave home.

So physical space is pretty important. The more you can be independent of your parents, the better. I wouldn't get a girlfriend just to prove your sexuality, but you might because women make good friends.