A weightlifter has trained for years and now has unusually large muscles. A student says that the weightlifter's children will be born with unusually large muscles too. Where does that reasoning go wrong?
Explanation
Training changes the body of the person doing it and leaves untouched the instructions that person hands to the next generation, so the children start from what they inherit and build their own muscles or not. The belief that a body changed by effort passes that change on is an old idea that observation does not support.