Wiktionary
what's good for the goose is good for the gander
prov. 1 What is good for a woman is equally good for a man; or, what a woman can have or do, so can a man have or do. This comes from an earlier proverb, “What’s sauce for the goose is sauce for the gander.” 2 What is good for one type is equally good for another type, despite any irrelevant differences between the types.