I was wondering if one theoretically wanted to start a new civilization
or colony somewhere, what would be the minimum number of people needed to
insure that there will no inbreeding? This assumes that there are no frozen
eggs or sperm or other such external aids. I know that royalty used to breed
within their lineage to keep the blood pure, but I also read that this lead
to a higher rate of children with health problems. Just two people? 
If you define “inbreeding” as pairing of first cousins or closer, you could get away with 8 people starting out a new civilization. In the fourth generation people would be marrying their Second Cousins, which should be be distant enough to avoid birth defects.
Mmmdamm you posted this exact same questiononly 3 days ago.
There were plenty of replies to your first post. It’s considered bad form to repost the same question in a new thread rather than simply continuing the old one. It’s also a bit rude to those of us who took the time to answer you first time.
Mmmdamm is new. Perhaps there are Board navigation difficulties?
I’ll close this thread and direct further comment to the earlier thread.
bibliophage
moderator GQ