I was just talking about this with my bf the other night. The topic we started out on was; "at what point do we expect people to overcome their upbringing?" Almost everyone was told something as a child that was purely their parent's opinion. Much of those things we don't bring into question until we become rebellious teens, and then we tend to knee jerk in the opposite direction, so I think that by 25, earlier for some, and later for others, we can assume that people have sorted through those things and formed their own opinions which they will in all likelihood pass on to their own children. I think that the environment we grow up in, great, good, fair or poor parents, economic status, etc, plays a large part in how we view the world. My parents were/are great people, everyone likes them that meets them darn near, and they are fun at parties, they were volunteer firemen, rescue squad, taught CPR and so on and so on, but they were fairly poor at parenting, just not made for it. I could write a book on why I believe that to be true and the underlying causes, but eventually I just had to own that and move on to becoming the best adult I could be despite that.
It's different for everyone but I DO think that it affects everyone to some degree.