when I was busy trying to learn what having a family was like
Good point - yes, children of, shall I say, "differently nurturing" parents are trying to learn what having a family is like and will go where the kindness seems to be. I can definitely think of two people from my childhood who fell in with us looking for something more family-like. It certainly gives you a different perspective than some people.
The people who become my friends, both then and now, seem to be people who have a different perspective. Some may have learned to survive less than optimum parenting. Other friends earned their different perspectives by being or feeling marginalized in one way or another. What about you? Would you say your closest friends have any common features?