once a..., always a...
once a (something), always a (something)
proverb A person's innate or fundamental nature is not something they are willing or able to change. He says he's trying to leave his life of crime behind, but once a criminal, always a criminal. Even years after leaving the stage, she still can't resist performing—once an actor, always an actor.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
once a..., always a...in certain respects people do not change, although circumstances change: He can’t resist explaining things in detail. Once a teacher, always a teacher.
Farlex Partner Idioms Dictionary © Farlex 2017