Hyphens, En Dashes, Em Dashes

Q. “One man-one woman family.” I’m editing a work and this looks wrong, but I can’t say why. Should it be a dash instead of a hyphen?

A. You’re right: the reason it looks wrong is that hyphens connect words to make phrases, and in your quotation, “man-one” doesn’t make sense as a phrase. The phrases you want to connect are “one man” and “one woman”: a one-man, one-woman family.