(something) runs in (someone's) family

When something "runs in" a family, it means that many people in the family share the same quality. The quality might be something physical:

Red hair runs in my family.

Or it could be a disease:

He told me that heart disease runs in his family.

Or it could be some personality trait:

Me and all my sisters have always been like this. Short tempers run in the family.

This phrase appears in these lessons: