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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

#51

Post by eru »

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 are hitting the borders where logic and common usage meet.

I am actually surprised that descriptive grammar holds up so well to logic. (There's no a priori reason why descriptive grammar, that describes common usage of language, actually is as mostly compressible to simple rules as it is.)

Re: Friends are as genetically similar as fourth cousins

#52

Post by [deleted] »

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?

[deleted]

Re: Friends are as genetically similar as fourth cousins

#53

Post by eru »

pliny wrote: post #43
hellofunk wrote: post #42

Earlier quoted context omitted.

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

That is less interesting, in the context of inbreeding, than any of them being products of first cousin marriage.

I think Roentgen, discoverer of x-rays, was the product of first cousins.

(I bet Wikipedia has a list of famous persons being children of first cousins.)

Re: Friends are as genetically similar as fourth cousins

#55

Post by usrusr »

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.

The beauty of selective enforcement. Dig deep enough into your ecclesiastical data-monopoly and you can veto just about any marriage at will. It never was the same again once laymen started to read and write.

Re: Friends are as genetically similar as fourth cousins

#56

Post by chaostheory »

Manishearth wrote: post #49
astazangasta wrote: post #36

Earlier quoted context omitted.

Yeah, which means the extensibility of these claims is exactly as good as those corrections, which can't possibly hope to model the missing information (the actual genetic distribution of friends).

Given that the US is a lot more racially heterogenous than the majority of the world (where the average person would have friends of a closer genetic makeup), I would bet that if anything these results are skewed the other way.

Exactly. These results would make sense in almost every part of the world, except the US.

Re: Friends are as genetically similar as fourth cousins

#57

Post by TeMPOraL »

mod wrote: post #27
Throwaway23412 wrote: post #25

Earlier quoted context omitted.

Edit: Nvm. I am more confused than I thought.

I've always wondered about this one: My father's first-cousin-once-removed is what to me?

http://www.wolframalpha.com/input/?i=father%27s+first+cousin...

First cousin twice removed, apparently.

Re: Friends are as genetically similar as fourth cousins

#58

Post by Jedd »

hellofunk wrote: post #42
mnbcvx wrote: post #18

Earlier quoted context omitted.

Yep. That's the kind of thing you look up at a young age when you discover you're the recent product of second cousins. Some interesting quotes from the "Cousin Marriage" Wikipedia article: "According to Professor Robin Fox of Rutgers University, it is likely that 80% of all marriages in history may have been between second cousins or closer." "Worldwide, more than 10% of marriages is between first and second cousins…

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 childhood, and only a couple going on to produce a further generation. (Not so uncommon these days, but at the time I believe this was quite noteworthy.)

Re: Friends are as genetically similar as fourth cousins

#59

Post by Noseshine »

Manishearth wrote: post #49
astazangasta wrote: post #36

Earlier quoted context omitted.

Yeah, which means the extensibility of these claims is exactly as good as those corrections, which can't possibly hope to model the missing information (the actual genetic distribution of friends).

Given that the US is a lot more racially heterogenous than the majority of the world (where the average person would have friends of a closer genetic makeup), I would bet that if anything these results are skewed the other way.

    > Given that the US is a lot more racially heterogenous
The US? Sure, but this isn't about the US.

The population chosen (or available) for the study does not reflect that diversity.

https://www.framinghamheartstudy.org/participants/index.php

    > The Original Cohort of the Framingham Heart Study consisted of 5,209 respondents
    > of a random sample of 2/3 of the adult population of Framingham, Massachusetts
So I don't understand why you point to diversity in some wider but not included group to reason about results based on the much more limited one.

Stratification doesn't help much - it doesn't generate missing data, it still is based on that limited population.

The study isn't "wrong" of course, it clearly states what data it is based on and what methods they employed. If there's anything wrong it's the interpretation by others. This is merely a hint "maybe worth having a closer look at this", it isn't meant to be used to draw any final conclusions from. Papers like this are for "internal use", for other researchers in the field, it should never go to the wider media. It's like a programmer showing their very first lines of code for a new idea, and then trying to draw conclusions about the quality of the final software to be released five years later, written by different people in a different programming language. Bad example, because here at least you already know what it will be about while in the study this remains open, so I reframed it to be about "(software) quality".

Re: Friends are as genetically similar as fourth cousins

#60

Post by tomtomtom777 »

LoSboccacc wrote: post #48

* fourth cousins genetically as diverse as random strangers would be a better wording the current title has implications not yet rigorously tested and people is already looking into selection bias to explain correlation where probably there's none.

> fourth cousins genetically as diverse as random strangers would be a better wording

That is not the same at all. From the abstract:

> More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people.

They specifically tested friends to include the general preference of friends to be similar.

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