A clan is consisted of two types of members: insider & outsider. A clan insider is generally a direct descendant of clan founders, and an insider is eligible to become the next headman (leader) of a clan regardless of gender & age.
An outsider is also a descendant of a clan, but his/her biological connection to a clan is weak. Sometimes, an outsider may not have any connection to a clan at all but his/her spouse has.
Case A: An insider marries someone who has no connection to his clan, his wife will automatically become an outsider.
Case B: An outsider marries someone who has no connection to his clan, his wife will also automatically become an outsider.
Case C: An insider marries an outsider, his wife will remain to be an outsider. They simply keep their clan status, vice versa.
If a child is born in case A, the child will become an insider.
If a child is born in case B, the child will become an outsider.
If a child is born in case C, the child will become an insider.
Both insider and outsider may claim their clan’s last name. However, outsiders in general do not proclaim their last name.
In rare cases, if a clan finds someone too valuable, a clan will convert him to an insider. Basically, a clan would adopt him into their clan legally.
The prime example is Masu whose legal name became Masu Bau after being converted into the Bau. A convert is never eligible to become a headman of a clan despite of being an insider. Of course, there was an exception in Masu.
Notable clans in Sol system
The Bau clan is #1 as far as number and dominance are concerned. The clan has over a billion members (Insider and outsider combined).
The O’ren clan is #2. They are based on Venus and has had a fierce rivalry with the Bau.
The Dietrich is #3 clan. They are based on Mars and are mostly miners. Their fierce rival is the Bau. They tend to maintain a positive relationship with the Klisis.
The Klisis sits on #4 spot despite of having merely a single member. This is due to Cecil Klisis’ influence and his ability to obliterate anything or anyone at will.
Notable clans in Andromeda system
In Andromeda cluster, it’s different situation compared to Sol system. There are no overly strong clans that rival local and federal governments.
Many clans exist within Andromeda cluster. However, none of them are dominant and are fairly small.
This is due to how the cluster was colonized. Only the poor immigrated to the area and clans that immigrated never had any financial and political powers to begin with. Furthermore, government structure of Andromeda union discouraged clans to become predominant.
A unique case: Pure blood clan
The Klisis clan was often called “Pure Blood clan” and sometimes called “Pure-bred clan”. The Klisis clan was a very small clan with their numbers never exceeding one thousand even at their golden era. However, all of their insiders were all at least class A ESP. It occurred at 99% rate. They were considered pure blood for ESP and any clans wanting ESP in their ranks arranged marriages with insiders of the Klisis clan.
The clan was also notorious for inbreeding in order to keep their “pure” blood as pure as possible. In fact, parents of Cecil Klisis were siblings from the same parents.
The Klisis clan was the only clan that wasn’t absorbed by the Bau on Earth. The clan eventually relocated to Venus in order to escape being absorbed by the Bau.
At the start of Two Clusters, the Klisis has only one member, Cecil Klisis.