I've seen many similarities with the group of friends I grew up with. Did we grow up and become more like each other or was our similarity (temperament, values) something that brought us together in the first place?

For example I was the first in our father's side of family to go into higher ed, but everyone in my group of pre-18 school friends ended up there. Many other groups in our school were characterized by other things like marrying young or seeking traditional blue collar jobs.

At least there was plenty of time for conversations to mold our thoughts. Parents might actually account for less than friends.