What is bred in the bone will never come out of the flesh

This saying is often misquoted and misconstrued. People say, ‘What’s bred in the bone will come out in the flesh’ meaning that a natural tendency cannot be restrained (e.g. Once a liar, always a liar). This is incorrect. The real meaning is to do with heredity: we inherit certain characteristics from our ancestors, and those same characteristics will be inherited from us by our descendants. Once it is ‘in the flesh’ it will never come out.

See also:

• Like father, like son