I think it’s funny how people judge who they think you’re related to. I’ve been asked if Duane and I are brothers (obviously, per this comic), Corey a few times and surprisingly Kevin once as well. I don’t really know the logic process that was going on for that one but I had a friend in preschool that had an Asian mom and white dad and he got all the asian genes and his sister got all the white genes so I guess it’s possible.
What has always interested me is how people that hang out with each other for a very long time start looking more and more similar as time goes on. Married couples exhibit this a lot as to long time friends and even people with their pets. My guess would be that it has to do with them being in a very similar environment and having very similar diets but who knows; maybe we’re all secretly the same person and just change based on what we grow up in.