LOL! But, hey, come on! There'd be no X-Men kids at all if everyone followed that rule!
That actually makes perfect sense. Another proof of Cyke's paternity! The Summers motto: Sleep with people who have tried to kill you/people you love/have successfully offed people you love/also make friends with them and have them on your team otherwise you'll just end up surrounded by people you trust who have never tried to kill you or anyone else and that would just be weird.