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Friends are as genetically similar as fourth cousins

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Re: Friends are as genetically similar as fourth cousins

#71

Post by jhbadger »

thaumasiotes wrote: post #50
runholm wrote: post #16

Earlier quoted context omitted.

Really not an issue with second cousins. Second cousins are genetically different enough that issues with the children are just barely more common in non-related couples.

What jacobolus said. First cousins are also genetically different enough that issues with the children are just barely more common than in unrelated couples. (The relative risk adjustment is quite high, but the absolute risk is still low.) If marrying your first cousin is a culturally accepted practice, it happens all the time and people get much more inbred than you might expect from looking at, or calculating from,…

But first-cousin marriages generation after generation are not a great idea, as happened in various royal houses of Europe in order to make sure both parents were of noble blood. In fact, it has been estimated that the last Hapsburg ruler of Spain, Charles II, ended up with more homozygous alleles than someone who was the offspring of siblings would. And he had numerous physical and mental problems that were probably the result of it.

Re: Friends are as genetically similar as fourth cousins

#72

Post by auganov »

Jedd wrote: post #58
hellofunk wrote: post #42

Earlier quoted context omitted.

Einsten, Darwin, and Giuliani all married their first cousins, from what I understand.

Darwin's family history is fascinating -- the intertwining with the Wedgewoods (as you note, Charles and Emma were first cousins), but doubtless exacerbated by the frequent first-cousin marriages in Emma Wedgewood's recent ancestry. Darwin was aware of the risks of inbreeding, and this marriage in particular, expressing those concerns in various writings. They had 9 or 10 children, IIRC, with 3 or 4 of them dying in…

Such a rate of childhood death would be high even for sibling parents. So perhaps there was something else going on.

Re: Friends are as genetically similar as fourth cousins

#75

Post by Snoooze »

compactmani wrote: post #54

The main finding from my perspective is that we can score and rank friendship likeliness and see signal in a hold out dataset. I can almost hear Facebook clamoring to offer free genotyping.

The dating world is already experimenting. (e.g. http://www.genepartner.com/)

Re: Friends are as genetically similar as fourth cousins

#76

Post by davnicwil »

avodonosov wrote: post #65
tempestn wrote: post #44

Earlier quoted context omitted.

That makes a lot of sense! The distinction between sibling and nth cousin is basically arbitrary. (Although obviously there is logic in making the distinction as well as in omitting it.)

Arbitrary? You have the same parents with sibling; with cousin you share only one of the two pairs of grandparents.

Actually that's often but not always true -

    brother b1 and sister s1 from family 1, with parents g1
    brother b2 and sister s2 from family 2, with parents g2
    s1 has child x with b2 - x has grandparents g1, g2
    s2 has child y with b1 - y has grandparents g1, g2
x and y are cousins, and also share the same 2 pairs of grandparents :-)

Re: Friends are as genetically similar as fourth cousins

#77

Post by moron4hire »

fiatjaf wrote: post #15
roninb wrote: post #3

In case you were also wondering what a "fourth cousin" was, someone who shares a pair of great-great-great grandparents[0]. Wikipedia has a great set of diagrams[1] in case you're also confused about first, second, or third cousins. I figure through induction you can presume any nth and nth removed from that page (I foolishly thought 3rd was where people arbitrarily stopped keeping count....) [0] https://www.referenc…

I get mad at people who think sons of first-cousins are second-cousins all the time -- and, frankly, almost everyone I know think this way. I'm glad you linked to this Wikipedia article that proves I'm not mad into thinking there is a simple logic pattern that can be applied to cousinship. However, this "once removed" notation is crazy. Why not second-uncle for parents of second-cousins and so on?

You get mad? Really? Why?

Re: Friends are as genetically similar as fourth cousins

#78

Post by skylan_q »

civilian wrote: post #39
milesskorpen wrote: post #26

Earlier quoted context omitted.

Sounds like they basically penalized record keeping ...

Ah, it was probably the Church who was keeping the records in the first place.

Yes, it was the Franciscans who were a huge influence and kept record of these things.

Most people would remember relations as far as great-grandparents and relations to families/family friends that they knew. Literacy was pretty high in the region early on as well, but people continued to rely on the church for recordkeeping.

Re: Friends are as genetically similar as fourth cousins

#79

Post by thegenius2000 »

fiatjaf wrote: post #15
roninb wrote: post #3

In case you were also wondering what a "fourth cousin" was, someone who shares a pair of great-great-great grandparents[0]. Wikipedia has a great set of diagrams[1] in case you're also confused about first, second, or third cousins. I figure through induction you can presume any nth and nth removed from that page (I foolishly thought 3rd was where people arbitrarily stopped keeping count....) [0] https://www.referenc…

I get mad at people who think sons of first-cousins are second-cousins all the time -- and, frankly, almost everyone I know think this way. I'm glad you linked to this Wikipedia article that proves I'm not mad into thinking there is a simple logic pattern that can be applied to cousinship. However, this "once removed" notation is crazy. Why not second-uncle for parents of second-cousins and so on?

Worse even, the "once removed" notation has no notion of direction, so it's inherently ambiguous. I'm also pretty sure that less half of the people I hear using it know what it means (or tries to mean).

Re: Friends are as genetically similar as fourth cousins

#80

Post by songshu »

fiatjaf wrote: post #70
rat87 wrote: post #24

Earlier quoted context omitted.

That's what I use. 2nd uncle, 2nd grand aunt Fun fact: in Russian a first cousin is a 2nd Brother/Sister, a 2nd cousin is a 3rd Brother/Sister and so on.

Thank you for being sane. Russians are decent people, it seems. Is the 2nd-uncle terminology widespread in Russia too?

Also good because it means you are your own 0th brother which makes sense. In the western version you are your own -1st cousin :(
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