Except that studies of twins raised apart[1] calculate statistical IQ heritability in the range of 70% or more. Perhaps even more surprising, for the field of Psychology at least[2], these findings appear to be replicated across studies. Even if you're not a full-on IQ apologetic, IQ is at least deeply correlated with success in professional fields, like engineering from your example.

As a parent myself, I wish the scenario you described was true! That guardians had the capacity to simply nurture into reality an Al Einstein or Mikey Phelps, if they just Tiger Mom push their way through the young person's early years. But the data do not indicate that; to the contrary, most of that future person is already defined in their nature/genes at conception, and good parenting, at its best, will simply avoid catastrophe while nudging towards good goals.

All the rest is just to make the guardian feel better about themself.

[1] https://www.science.org/doi/10.1126/science.2218526 [2] https://en.wikipedia.org/wiki/Replication_crisis

ad hominem

Neurons specifically.