My two older sisters have had sex with their boyfriends when they were in high school, and I bet my younger brother thought that was cool too. Old parents often screw because they feel like they can't do anything by themselves, like their children will be put in danger if they act out. Older people sometimes screw because they feel like they are failures, or because they are too scared to stand up to their own passions. Whatever the reason is, I think we can all agree that screwing an older relative is pretty messed up. Here's how you can deal with your own screw:.