A Scottish Clan is a tribal concept, generally meaning an
extended family all related by birth. A Clan is usually named
for one person -- for example, Clan Mackenzie derives its name
from Kenneth, its Progenitor. In theory, all Clan members are
descended from him. In reality, some may not be, as over time a
Clan may have been joined by other people. The seniormost branch
of the family is the direct line of descent from the Progenitor
to the current Chief [this is where the concept of tanistry
meets the concept of primogeniture]. The senior branches of the
family, or cadets, generally signify a subgroup, or family, that
each descend from one of the Chief's sons. The affiliated
branches, the septs, are often said to be unrelated by those who
assume that a sept's allegiance to the Chief was a matter of
safety during dangerous times. In fact, members of the septs are
often the descendants of the Chief's daughters. Only DNA tests
can show these relationships, but descendants of the septs would
then show up as havi