AI: It is a well-known fact that the heritability of IQ increases with age. While children live with their parents, their parents influence their IQ quite noticeably; more than a third of the variance in IQ is explained by the environment created by the parents. However, as you grow older, there is practically nothing left of external influence on IQ. By the age of seventy, 70-80% of IQ is genes.
Interestingly, with character everything is exactly the opposite. In childhood, most of the character is genes, but the older a person gets, the more influence of the environment is noticeable in the character. Character is much more flexible than IQ.