I agree with Leon (and pretty much everyone who has posted here) We are products of our environment, which drives our choices, but then those choices affect our environment as well, altering what choices we face next.
For example, if I was raised in a house with exquisite manners then those manners will be like second nature to me. I have to choose them each time in order to make them happen, but I mostly choose them unconsciously. I could choose to not use them. Compare that to a person who was not raised around manners at all and has to put forth the effort to choose manners, not only in the moment, but also choosing to watch others closely enough to learn the manners that were never taught. Chances are, that person is still not going to carry those manners as graciously as the person who was raised around them, but still makes a choice to use the best manners that he can. Now think of how the choices affect environment. The one with exquisite manners who chooses to use those manners will likely be noticed and probably offered opportunities. The guy with exquisite manners who chooses not to use them will come off as a total a** and likely not be offered many opportunities or will be offered some out of other people's fear of what he might do. He also will likely lack in friendships. The guy raised without manners who chooses to put forth the effort will have friends and some opportunities, though not as plentiful as the first guy and probably not as lucrative. It is doubtful he will be easily noticed as standing out from the crowd. The fourth guy, raised without manners and continuing to be oblivious to that fact will have a hard way to go in life, with few friends and few opportunities, and will be no the wiser regarding the choice he had in the matter.
All products of their environments, working within the constraints of their environments and altering their environments by their choices, which further affects their choices and those of the next generation.