Romans scarcely ever used 'family' in this modern sense, it usually meant 'household retinue' or 'ancestral property'.
Just checking, shouldn't it be "Familia mea Romae habitant ", as in "My family they live in Rome"?
Actually, "family" can be both singular or plural. But family in this context is most likely a group of people. If Latin preserves person and number in the verb, shouldn't the verb in this case be plural? For example, "mea familia currit" translates as "My family, it runs", which is grammatically incorrect, versus "mea familia currunt" - my family, they run.
-- Edit -- Apparently the verb is actually singular. Just looks strange.