Spoiler
Actually in Bio 1 your a fast grown clone of Andrew Ryan and you fly out to see your "parents" (Frank Fontain's project) because of an important date in your head, pre-programed if you will, and you become a splicer in order to become a big daddy in the end kinda like Delta

Spoiler
In Bio 2 you were a man that found Rapture and was forced to become a big Daddy, you retain your "heart or lack of one" and then become a new man that influences Elenore into either a good or bad person... then you die or live if your evil


If you saw like a little sister then you'd probably walk you and give a turret a hug... good luck with that