I've heard a number of people, mostly young microbrew knowitalls and homebrewers, claim that hops are in the same family as, and in many ways similar to, that other popular budding plant.
I hate know-it-alls as much as the next guy but...
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales
Family: Cannabaceae
Genus: Humulus
Species: H. lupulus