[for a characteristic] to appear in many (or all) members of a family. My grandparents lived well into their nineties, and it runs in the family. My brothers and I have red hair. It runs in the family.
to be a common quality among members of a particular family His father and uncle were basketball stars in college, so athletic ability runs in the family.
if a particular quality or ability runs in the family, a lot of people in that family have it Athletic ability runs in the family: his father played basketball in college and his mother was a high school athlete.