Assuming someone is a particular way DUE to their culture, family background, or ANY other personal attribute is deterministic and should be avoided (this is probably also a Postmodernist stance!).
Having been imbued with a good dose of Postmodernism--as we all have, whether we understand this or not--I would say that, today, each one of us lives in a self-created, individualistic (Postmodernist) world, to one degree or another. True, yours might be further from the "mainstream" than most, but since Postmodern thought is highly skeptical of what's called "grand narrative," each individual is freer to create her own reality in an age of increasing individuation.
The term hybridity is used to explain this condition. For example, non-Native Americans can study Native American thought and lifeways. It would be easy to dismiss the former because they are NOT Native American people and they are not truly living a "Native American life," but that's my point: people are free to piece together--hybridize--their own created identities from whatever they choose.
This is a fairly new development. I would say that BECAUSE I am a middle-class, Caucasian, late-middle-age male raised in a milieu of Christian upbringing does NOT define much about me anymore. I am free to choose otherwise. I am free to create my own (new) persona, based on a smorgasbord of possibilities. (For example, I label myself "pagan-Buddhist-Christian," normally an oxymoron, but a label that has meaning for me.) This is one aspect of a Postmodernist society: self-created meaning and identity.
To understand Postmodernism one would have to understand the historical era described as "Modern" (some thinkers reject that we are really in a "post-" period after Modernism, and that we are in a "late-" or "hyper-" Modern period), which was based on ideals which came out of the Age of Reason (or the Enlightenment) of the 17th and 18th centuries. To take one of its ideals, there is the idea of Progress: that society could be perfected through the gradual perfection of humanity. Postmodernist thought is highly skeptical of this ideal, instead seeing within society increasing pessimism and irrationality.
There is so much more to Postmodernist ideas, but the area I am interested in academically is how we see and experience place and space (including cyberspace) and how this impacts identity and spatial cognition. To give one idea, we are increasingly "placeless" and tend toward a rootless nomadism, not bound to a single place. We are losing our sense of place to a single place in one degree or another and acquiring a sense of "glocal" space--a cognitive continuum from local to global, or so I theorize.