The family unit is very important in the cultus deorum, but there were and are several different units. In addition to the “family” as we understand it, there was also the “household”, which included everyone living under the same roof, and the “clan” (Latin: gens), the collection of families with the same name. An interesting feature of Roman clans is that each one had its own traditions, its own sacra (rites) that were peculiar to it.
The head of the household (called the pater familias or mater familias) performs the duties of priest, with the assistance of the household members.
Family connections do not end with death. As with many religions of the world, we view our deceased ancestors as contributing importantly to our well-being. Many keep portraits of their deceased family members in or near their lararium. Offerings are made to them in order to maintain a positive relationship.
The Parentalia (February 13th and continuing through February 22nd) is the festival in honor of the Dii Parentes. It was immediately followed by the Caristia.
The household has its own special gods, as does every aspect of the world. The Lares and Penates, protectors of the household, are worshiped at the lararium. Vesta also has a special place in the household, often in the kitchen, which serves us as a modern hearth.
Each person belongs to a household and to a clan, and so participates in the rites (sacra) belonging to those groups. Likewise, membership in various communities brings participation in the sacra of those communities.