Tribal houses of the Drifters.
There are two groupings, Major and Minor Clans. Major Clans have been around for centuries, and attempt, though somewhat strangely, to trace their lineage back to prominent families and organizations that abandoned Earth for the stars.
Clans are a tight affiliation, and are by no means exclusive, they mingle with each other and freely intermarry/associate as business takes them. At the head of each clan is generally a Matriarch, who presides over all the Clan dealings.