Clans claim shared ancestors even when the pedigree is mythical
A clan unites people by actual or perceived kinship and descent from an apical ancestor who symbolizes the group. English borrowed Gaelic clann—children or descendants—around 1406 to describe Scottish Highland organization. Many societies ban marrying within one's clan as incest.
Members may trace themselves to a founder whose actual lineage is unknown, and some groups name a stipulated ancestor, often an animal that older anthropologists such as Gerardus van der Leeuw classed as a totem. Clans predate centralised government and have existed in every country, frequently rallying around a coat of arms or similar emblem. Marriage bans can extend beyond one's own clan to those of both parents or even grandparents.
What usually separates a clan from a tribe or band is that it forms a smaller, integral piece of a bigger social unit, whether a tribe, a chiefdom or a state. Some have a formal chief, matriarch or patriarch, others defer to elders, and elsewhere leadership must be earned. In Gaelic itself, clann simply means children, and kin groups go by other words, such as teaghlach for the family under one roof and muintir for kinsfolk in the broad sense.
Irish clans, or fine, joined a chief and his patrilineal relatives with unrelated clients who took the leading family's surname as a sign of loyalty but could never be elected chief. Polish clans are instead families sharing one coat of arms, and Romani clans are called vitsa. In the African Great Lakes region the clan is the oldest social structure after family and lineage: Rwanda has twenty, split into subclans, and Nkore just four. In post-Soviet countries the word is used loosely for informal economic and political networks, and it is applied to some organised-crime groups as well.
Source: Clan
