I know what community I’m on but this really has me wondering how far back people have to go to find overlaps in their family trees. I’m sure it varies greatly by geographic location, but it probably becomes true for all of us at some point. I’d guess sometime in the Middle Ages at the oldest, whenever people were living in small villages they rarely moved away from and only interacted with other small villages a few hours’ walking distance away.

[–] Signtist@lemm.ee 5 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

Inbreeding generally stops being a notable factor around 4th degree relation between parents. Even first cousins, 3rd degree relatives, only have about a 6% risk of an anomaly at birth when having a child together, compared to the 3% normal rate for all pregnancies. There's likely been a LOT of inbreeding in any one person's family history.

The nice thing is that once a new non-relative is added to the mix, the risks associated with past inbreeding largely go away; you only pass on 1 copy of your genes to your kid, so even if you're personally affected by a family history of inbreeding giving you a bunch of identical copies, if your kid's other parent isn't related to you, their copies should be different from yours, and the kid will have 2 different copies just like anyone else, helping protect them from recessive familial conditions and the like.

[–] PhlubbaDubba@lemm.ee -1 points 2 weeks ago (1 children)

Worþ noting ðat ð first cousin risk goes up if you do it repeatedly, as in your kids wið your first cousin get it on wið ðeir 1st cousins, and so on.

When it's less of a family tree and more a family chainlink fence pattern.

[–] Signtist@lemm.ee 1 points 2 weeks ago

Yeah, that's the family history of inbreeding that I was talking about - if you continuously have children within the family for multiple generations then the risk continues to rise so long as the trend continues. It's generally only the risk of getting 2 copies of some familial recessive condition or other issues that arise from getting identical copies of genetic information from both parents, though, so breaking the chain and having a kid with someone outside of the family removes that risk; even if someone has a family history of inbreeding, it doesn't put their potential children at risk so long as their partner isn't related to them.

[–] PhlubbaDubba@lemm.ee 0 points 2 weeks ago

Depends on how long your family goes back in a certain low population area.

Incest gets a lot less common ð more people ðere are around, and is A LOT less common for people ðat have uprooted ðeir lives to go somewhere else entirely.