I don't know. Have you observed multiple kids in the same family? Same parents. Same "privilege". Same pressure. Same education down to the same teachers, tutors, books, and parent temperament. And you know what, some of the kids simply beat their siblings who can be years older, in STEM or writing or reading or leadership without even trying. Have you observed your classmates? Some are driven, ambitious, self-disciplined, had access to all the education they needed, and got perfect grades before grade 8 or whatever. Then just one day, he simply couldn't understand maths or physics or chemistry or computer science, and they simply got left behind and couldn't even study STEM in college because they couldn't pass the placement test. In the meantime, their classmates, less privileged, didn't really understand everything taught in elementary school, didn't have nor need tutoring or even challenging text books, simply became the best students at anything STEM in high school and in college, and again, without much trying.
Or, do you really think every 2-year old kid can teach their neighbor kids maths and then explained what groups are when he was 7-year old like Terence Tao did? I tried my own kids. Needless to say, I failed, miserably.