inbreeding leads to less genetic variety, not more. anyway everyone is already related. pedigree collapse. you have two unique parents. assuming no incest you have four unique grandparents. eight great-grandparents. and so on. the number of uniques ancestors per generation doubles every generation assuming no incest. the problem is, once you get back to around the year 1200CE, the number of unique ancestors you are supposed to have outnumbers the population of the entire planet at that time. so clearly there was some incest going on. And that's only back of the envelope math. the rate of inbreeding is probably higher than this math suggests, once you account for the fact that most people prior to the industrial revolution usually ended up mating with someone within walking distance, probably a 3rd or 4th cousin. also obviously the geographical divides between continents.
inbreeding leads to less genetic variety, not more. anyway everyone is already related. pedigree collapse. you have two unique parents. assuming no incest you have four unique grandparents. eight great-grandparents. and so on. the number of uniques ancestors per generation doubles every generation assuming no incest. the problem is, once you get back to around the year 1200CE, the number of unique ancestors you are supposed to have outnumbers the population of the entire planet at that time. so clearly there was some incest going on. And that's only back of the envelope math. the rate of inbreeding is probably higher than this math suggests, once you account for the fact that most people prior to the industrial revolution usually ended up mating with someone within walking distance, probably a 3rd or 4th cousin. also obviously the geographical divides between continents.
https://www.youtube.com/watch?v=mnYSMhR3jCI