Does 19th century Australia have a very limited gene pool ?

Question

I have recently taken the DNA Test , and have been "rewarded" with nany DNA matches in the 3rd cousin or more distant category.  In looking at the Australian matches, I have found six people with whom I have a connection in the 3rd cousin or further category - a good result. These connections have been revealed by the genealogy program GENI, and all are such that the DNA cannot possibly  be shared by the revealed connection.  That is, there are too many connections througg marriage, with no direct path for DNA inheritance.

Has anyone else experienced this ?  Do you think the DNA matches are genuinely shared through inheritance, or could there be common sequences by chance in my ancestors, which are almost exclusively Irish and English ?

Your comments, observatiins and advice are welcome.

Comments

Assuming these are decent 7cm segments, not itsy-bitsy ambiguous scraps, they can possibly come from recent cousin-marriages in Australia, otherwise they're what they should be.

Answer 1

Australia as a whole does not have a limited gene pool, but certainly sub regions can.

Western Australia had very few white settlers until the 1890s and when you stratify by geography and class, you get a bunch of cousin marriages. More to the point for your question in my tree you get people that are not cousins to each other but who are both cousins to me marrying each other.

I've found the same thing in my partner's tree in the southern Darling Downs, very complex interrelationships.

I'm not actually sure how that would look in DNA results to be honest.

Of course one or more of the trees you're comparing to could be plain wrong.

Also the cousin distance is always just an estimate, although a sixth cousin match coming up as a third cousin match is pretty unlikely.

Comments

Interestingly, Mark, it it the Darling Downs branch of my ancestors which has many of these complex interactions.  If the Sydney ancestors have similar connections, I have yet to uncover them.