Maimonides

If a person studies too much and exhausts his reflective powers, he will be confused, and will not be able to apprehend even that which had been within the power of his apprehension. For the powers of the body are all alike in this respect.

If a man made himself an expert in any particular branch of human activity, there would result the strong tendency that a peculiar aptitude towards the same branch would be found among some of his descendants.