There is apparently a popular Irish joke of this guy coming to a roadblock during The Troubles. The militants at the roadblock as him his religion and he says "atheist." The militants talk amongst themselves, then ask him "Protestant atheist or Catholic atheist?" It may be a sad joke but it sums up how important one's background is. A Protestant atheist (an atheist of a Protestant background) would have different values, at least when it comes to disbelieving, than a Catholic atheist. And a Hindu atheist would be radically different! Where you come from, no matter how far away you are from it, affects how you approach things now.
The impact of background affects more than just religion, it works with fluid gender and sexual orientation. I strongly identify as genderqueer and my background of woman/lesbian affects my approach today, so I'm most accurately a female-to-queer. Had I come from the background of a man, I'd approach things differently. Coming from an intersexed or gender-free background would have been...optimal. Anyway, I'm usually most comfortable with feminine pronouns, the women's washroom, etc. because I'm used to it. Sometimes I'm frustrated that there are too few non-binary options; it's frustrating enough being perceived as a woman in the first place since this isn't exactly an egalitarian culture! A lot of transsexuals who "successfully pass" experience culture shock as they have to change how they approach things.
I'm usually comfortable functioning as a lesbian since that's my background and it's a lot easier to give the short answer "I'm a dyke" to n00bs than the long explanation "I'm genderqueer and I'm primarily attracted to fellow genderqueers...oh, you haven't heard the term before...etc." And then they get confused when I ogle Chris Colfer...I mean...what?