#StackBounty: #intelligence How to interpret genetic variance of IQ?

Bounty: 100

I am a layperson currently reading "The Bell Curve" and its various rebuttals such as "The Intelligence and How to get it". I do not want to go into controversies of the topics per se and those are irrelevant to my question.

To quote from Wikipedia:

"Heritability" is defined as the proportion of variance in a trait which is attributable to genetic variation within a defined population in a specific environment.1 Heritability takes a value ranging from 0 to 1; a heritability of 1 indicates that all variation in the trait in question is genetic in origin and a heritability of 0 indicates that none of the variation is genetic.

If for the sake of this question, if I were to assume heritability is 0.5, then is it right to understand that there is a 50% chance that I could have inherited my intelligence (as measured using standardised IQ test) and another 50% chance that my intelligence is not inherited? I also read that genes set the upper limit of intelligence, in which case is it right to assume that if a person did not inherit her intelligence because she falls into the latter group, are her limits of intelligence determined entirely by environment and education (or do genes still play a smaller role?).

I appreciate that the extent of heritability is scientifically debated among experts, but I am interested to know what is the debate really about and how to interpret the arguments related to nature vs. nurture. To explain my confusion further – a person who is only 170 cm likely inherited his height from his parents who are only 165 cm. A bit of extra height may have come from better nutrition (than a generation ago) which is an environmental factor. What would be a similar example when it comes to IQ?

Get this bounty!!!

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