I don't necessarily think that if you hang around smart people you will become smart, as such.
I prefer the statement: the persons who you surround yourself shape the person who you become. If you are in a group with all 'A' students, and you don't get quite that high you may strive to raise your mark from a 'B' to an 'A' but that does not mean your intellect as such will increase. It goes the opposite way aswell. If an 'A' student is in a group with 'D' students, then the 'A' student may not get stupider, they may just not be motivated to work as hard.