I don't think you can blanketly say that picky eaters are a result of their upbringing.

My brother and I grew up in a mish-mash of cultures and was exposed to many different things. I usually liked to try different foods and surprised people when I liked things traditionally not liked by children (natto and salmon roe for starters).

My brother, on the other hand, was a PICKY eater. Didn't like this, didn't want to try that, etc etc. We couldn't be more different in terms of our tastes.

He did eventually "outgrow" his pickiness and he'll eat pretty much anything now. But he's got his payback; his elder daughter is just like he was and is super picky. I'd say in this case the pickiness is genetic!