Consider genetics as a ceiling. An upper bound. Take the same child, give it an "ideal" upbringing or an abusive upbringing. You're going to get different IQ s

Consider genetics as a ceiling. An upper bound. Take the same child, give it an "ideal" upbringing or an abusive upbringing. You're going to get different IQ scores out of the adult. I believe you can see this in the Flynn Effect.