Everyone's upbringing is unique. So is everyone's family, where they live, their belief systems and values (which is largely passed on to them by their families) and the people they have been exposed to
There is also the randomness factor, which is what differentiates me and my brother even though we live and have lived pretty much the same life. I read and watched stuff that he didn't and doesn't, and he read and watched stuff that I didn't and don't, and now we have different beliefs, different outlooks to life, different dreams, different music tastes, different habits and so on