Keep in mind I'm not saying it's a deterministic inherited thing (it's clearly not). However I believe there is strong evidence that everyone is born with a unique personality and potential. An "environmental chaos theory" does not do justice to unexplained outliers, those with recognized mind-affecting genetic conditions, and many other real-world scenarios.
My situation is even more unusual than you realize. I didn't even meet many people while growing up; throughout my childhood I was almost entirely separated from the outside world (lived secluded in the mountains). Almost no neighbors near by. I never went to public school. Extremely protective parents did not allow us to ever talk to strangers. All this is the same case for my siblings, yet they have no desire to pursue technology, while I do.
Note that by no means am I trying to downplay the importance of environment. I'm simply trying to illustrate that the claim "environment determines 100% of someone's mental and personality development" is empirically wrong.