Of course, the "answer" is we focus on them because we kn ow they are troubled and want to "abuse" them.
Let's be real though.
This girl is 12ish and has a very troubled upbringing. I didn't really put any focus on her, but she just... is drawn to me. We just start hitting it off and I have become an incredibly helpful rock for her and helped stabilize her life for the time being.
Which leads into why I think they are drawn to us, that was our evolutionary purpose. The troubled kids, the orphans, the ones no one wants to deal with... we dealt with. We had an instinctual basis to want to be near them.