
Friends Are Genetically Similar (2014) - jacobr
https://www.nature.com/scitable/blog/accumulating-glitches/friends_are_genetically_similar
======
abra_kadabra
This is interesting as I've typically made friends along lines of interest. I
guess my next question would be are genetically similar people more likely to
have similar interests.

edit: corrected grammer

~~~
fatjokes
> I guess my next question would be are genetically people that have genetic
> similarities more likely to have similar interests.

If that is the case, it would lead to the politically uncomfortable question
of different genders or ethnic groups being more likely to have particular
interests.

~~~
flatline
I think it's trivially obvious that they do?

The uncomfortable questions are whether people are genetically predisposed to,
or naturally have a greater aptitude for, some particular interest,
particularly on racial or gender lines. For many physical activities this is a
settled question for gender, but that's about all we know.

Even this alone is not necessarily controversial, the problem as we've seen
time and again is that the reaults of such a study are taken as a basis for
discrimination. If we could rigorously quantify and prove a statement like
"people of East Asian descent show a 2.3% greater aptitude for mathematics,"
it doesn't mean that the Chinese guy sitting in front of you has any such
aptitude. Historically the metrics by which we have attempted to measure such
things have been deeply flawed and biased. I'm not sure it will ever be
possible to make such assertions in any rigorous manner, the factors behind
cognitive tasks are just too complex.

~~~
RivieraKid
> The uncomfortable questions are whether people are genetically predisposed
> to, or naturally have a greater aptitude for, some particular interest,
> particularly on racial or gender lines.

The answer is obvious here: yes. The only question is the size of the effect.

~~~
i_cannot_hack
> The answer is obvious here: yes.

Let's say the statistical size of the effect is something around a millionth
of a millionth of a percent, then I think most people would answer the
question with "no" and be understood correctly by everyone. These kinds of
questions almost always have a "big enough to have a perceptible
impact"-clause implied. Pretending they don't feels needlessly pedantic.

~~~
aaron695
I took the comment as saying obviously it's not "millionth of a millionth of a
percent". You are strawpersoning here.

There are going to be definite real world measurable differences.

OP leaves open the possibility, for instance, of cultural differences that
have a effect an order or two of magnitude larger though.

Personally I doubt this, but OP seems open to the idea the size might be
small.

~~~
i_cannot_hack
In that case I would like them to define a lower bound of a "measurable
difference" and give a clear case why the effect is obviously higher than
that. Simply saying it's obvious when many people actually disagree is not
very constructive.

I'm not saying they are wrong, I just disagree with the tone.

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choxi
> The tendency for friends to have similar genomes might result from people
> befriending those of similar ancestry, but the duo are confident that isn't
> the case. Not only did they control for the effect of population structure
> and ancestry, but the Framingham data is relatively homogeneous in terms of
> ethnicity, consisting largely of people of European descent.

How did they control it? Even amongst Europeans, I imagine French people are
just more likely to have French friends.

~~~
gph
Framingham, MA is old school New England. I wouldn't be surprised if 75+% of
the participants are of direct English/Anglo-Saxon descent, even though the
article describes it as "European" descent.

~~~
QAPereo
Framingham is pretty much just like that, although it's less than 75% it's
still a supermajority.

[https://datausa.io/profile/geo/framingham-
ma/#demographics](https://datausa.io/profile/geo/framingham-ma/#demographics)

~~~
gph
Remember also that the dataset they are using began back in the 1940s when the
towns demographics would have been much farther skewed towards English/Anglo-
Saxon. And while they've included more participants over the course of the
study, it's mainly been adding the descendants of the original participants.

~~~
QAPereo
Good points, but either way the go study is doubtful as hell.

------
okreallywtf
I have anecdotally noticed this with tall people and short people, I will
notice a group of friends who are all 6'2"+, or who are all <=5'7", both of
which seem statistically unlikely. There are plenty of more diverse groups (in
terms of height) but its hard to say whether they are work friends or
something else where you have less overall choice.

~~~
jawns
A few possible explanations:

* People who are statistical outliers tend to seek out similar outliers to form a support network.

* People who are involved in activities in which their physical size is pertinent (e.g. dancers in the Rockettes) tend to befriend others in those activities.

* If height affects success (whether or not that is warranted) and if friendships are stratified along success-based lines, then you might expect groups of friends to have similarities in height.

~~~
vidarh
Also: One might be more likely to _notice_ groups of mostly tall or mostly
short people more than generic, mixed groups.

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jfinmaniv
_" The opposite pattern held for genes related to immunity -- friends tended
to be less similar at those parts of the genome."_

It would have been more accurate to title this article "Friends Are
Genetically Similar in Some Ways and Different in Others" but I guess that
would not have been as edgy.

EDIT: The overall trend reported is that friends are more genetically similar
than would be expected, as pointed out by user _Real_S_. Good title, after
all.

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sillysaurus3
It would be interesting to cross-reference this with the genetic dissimilarity
between enemies, but that's problematic for obvious reasons.

~~~
i_cant_speel
Yeah I agree the results would be interesting as well as hard to collect.

If I were to volunteer for this study, all of my 'enemies' (more just people I
don't care for) would either be people who I haven't seen in forever because I
don't want to associate with them or people that I see too often that I
wouldn't want to bluntly declare as my enemy and deal with the consequences.

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mancerayder
The study mentions the 1% similarity, which is the genetic equivalent of
fourth cousins. That's fine, but isn't there a heavy correlation between DNA
origin and geography, and another correlation between friendship and
geography??

~~~
rjurney
Also friendship and family are tied together. I would think they controlled
for these things? I did not read the paper.

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vorg
There was a book I read in the 1970's about "sociobiology" that explained
this. If I remember right:

People share exactly 50% of their genes with their parents and children, but
only _probably_ 50% of genes with siblings -- it could be 51%, or could be
48%. To preserve their own genes, people will feel altruistic to give their
lives for three of their siblings (about 150% of their own genes saved), but
not for one sibling (only about 50% saved). People share between 90% to 110%
of their genes with two siblings (I'm guessing the variance here), so will
give their lives for two siblings they share 110% of their genes with, but not
two they only share 90% with. The feeling of "liking a sibling as a friend" is
the same as being willing to give one's live for them, so in today's age of
large urban groups where friendship is a proxy for one's siblings in small
tribes during the hunter-gatherer era, it follows people choose their friends
_because_ they share more than the average genetic material with them.

~~~
tzs
> People share exactly 50% of their genes with their parents and children, but
> only probably 50% of genes with siblings -- it could be 51%, or could be
> 48%.

I don't see why the percent shared could not be higher than 50% with your
parents or children. You can share a gene with someone that you did not get it
from or give it to. For example, suppose some particular gene has three
variants, V1, V2, and V3. If your mother has V1/V2, and your father has V2/V3,
the possible cases for you are V1/V2, V1/V3, V2/V2, and V2/V3.

In two of those cases you share 50% of that gene with each parent. In the
other two cases you share 50% with one parent and 100% with the other parent.

~~~
vorg
What I wrote is what I got from reading the book a long time ago. Of course
biology has advanced since the 1970's -- and of course my memory or
understanding of it could be faulty because I read it as a teenager.

What you wrote might explain why parents have "favorite" children they're more
likely to give their life for.

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rxaxm
> Topping the list for common genes were those related to our sense of smell.
> One explanation for this is that people with similar olfactory genes will
> smell things in the same way and so be drawn to (or repulsed by) similar
> environments... The opposite pattern held for genes related to immunity --
> friends tended to be less similar at those parts of the genome.

This makes me think of the thesis of "Sex At Dawn" by Christopher Ryan and
Cacilda Jetha. If humans evolved as polyamorous foragers for whom communal
bonds were more important than paternal certainty, then it makes sense that
you want your friends to like the same environments and add immunological
diversity to your shared gene pool.

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throwaway832852
The same is true of spouses, and in fact, the healthiest couples (or at least
those with the most children) seem to be third or fourth cousins:

"Third Cousins Have Greatest Number Of Offspring, Data From Iceland Shows"

[https://www.sciencedaily.com/releases/2008/02/080207140855.h...](https://www.sciencedaily.com/releases/2008/02/080207140855.htm)

Not exactly what you'd expect given how often we see "hybrid vigor" touted as
a purported benefit of interracial marriage.

~~~
jinfiesto
Yeah, I think "hybrid vigor" is probably nonsense. However, interracial
couples tend to be left-leaning, which also implies fewer children, so I don't
think it makes sense to infer causality (or lack thereof) the way you are. Too
many competing factors.

~~~
throwaway832852
At a minimum, the study suggests that the fitness golden mean between
inbreeding depression and outbreeding depression is actually much closer to
the intraracial side of the spectrum than the interracial.

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azinman2
Basing this on the Framingham study doesn’t say much. We do know homophily is
very common world-wide, but Boston in particular is extremely segregated. Out
in the burbs it’ll be largely small pools of ethnic (European) groups. While
the summary at least touches on this, it would totally flop in diverse areas
like SF or NYC. Most of my friends are from all around the world — if they all
still shared some genes in a way that was uncommon I’d be extremely surprised.

------
InclinedPlane
Reminds me of this: [http://www.neatorama.com/2013/12/15/When-the-Actors-in-
Plane...](http://www.neatorama.com/2013/12/15/When-the-Actors-in-Planet-of-
the-Apes-Donned-Their-Makeup-They-Spontaneously--Segregated-Themselves/)

Humans are still amazingly tribal creatures.

------
ThomPete
Anyone know if the genetic similarities that we become friends around
according to the study aren't related to race? To me that would be the most
interesting part (if it wasn't).

I am pretty sceptic about this study and it seems kind of filled with
opportunity for interpretation and bias plus have no idea of the data set.

~~~
canoebuilder
As other's have mentioned in this thread I believe the group under study were
primarily, if not all, Europeans. So in that case in a sense the genetic
similarites weren't related to race because race wasn't a variable.

But as far the relation of genetics and genetic similarities to race, all
genetics are related to race.

In terms of the fact that a single Adenine molecule alone is fairly useless,
it is only when that molecule is combined into the structure of a genome that
it takes on meaning[0], and genomes have a race, so I don't think in that
sense there are any genes or genetic similarities that aren't related to race.

Every member of a race is more genetically related to every other member of
that race than they are to any member of any other race.

What "genetic similarities" could there be that are more similar across races
than within races?

[0]"Meaning" at the level under discussion in terms of human relationships and
whatnot.

------
beepboopbeep
I figured friends were more driven by proximity first then shared experiences
second.

~~~
saalweachter
This is the rare study I'd be really interested to see repeated with college
students.

The population used in this study was the population in the Framingham Heart
Study, presumably because they had the DNA and friendship graph already lying
around. But starting from a small town's population, you've got pre-existing
social networks which will both influence the future genetics and the future
social networks of the town. You could get a lot of confounding correlations
like "you're more likely to be friends with someone you live nearby to and
you're more likely to live nearby to people you are related to".

If you repeated this with college students you'd have friendships formed
between people with few if any previous connections.

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elchief
And don't we fall in love with people that are genetically different?
Something about not liking the smell of relatives

~~~
canoebuilder
Only in the genetically different immune systems as discussed in this article,
otherwise opposites don't really attract. I don't think it would be that
surprising to find similar results(maybe less, but still greater than random
in terms of similarity) among married couples.

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haberman
This seems to make the kin selection vs. group selection controversy even more
trivial: [https://blog.oup.com/2015/01/kin-group-selection-
controversy...](https://blog.oup.com/2015/01/kin-group-selection-controversy/)

------
cyberferret
Hmmm... As someone of sub-continental heritage, I have close friends from
about 3 different ethnic groups. I have NO friends from my own
cultural/regional heritage at all in 5 decades of walking this planet.

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smortaz
Study summary in one picture :)

[https://iwsmt-content-
ok2nbdvvyp8jbrhdp.stackpathdns.com/525...](https://iwsmt-content-
ok2nbdvvyp8jbrhdp.stackpathdns.com/52520132332151.jpg)

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horsecaptin
Does this mean that if you have similar experiences, then your genes change? I
have found that experiencing things together forms friendships much more than
genes.

------
canoebuilder
Is it anymore likely that people with 1% genetic similarity have that
connection randomly than the possibility they in fact share g-g-great-
grandparents? i.e. 2 slots in the 32 level of their family tree, or what if
they are double fifth cousins, sharing four slots at the 64 level?(is that
math correct?)

So in effect for these similarities to present, they have to be cousins on
some level right? Whether that is sharing N slots at the 2048 level, or some
other combination?

In a sense all of humanity are cousins, and races are clusters with a higher
coefficient of cousin-ness than the global average.

------
nyolfen
i found out recently that my lifelong best friend and i share a relatively
uncommon paternal haplogroup, despite our families coming respectively from
germany and scotland for the most part (the group is relatively prominent in
frisia). anecdote, not data obviously, but i'm curious if anyone else has any
similar experiences.

~~~
mmanfrin
R-M405? Me too; but my paternal line hails from Venice. Seems our forebears
scattered around.

------
dominotw
friends are economically similar and how much money you make relative to the
rest of the society depends almost entirely on how much money your parents
made relative to the society. Wealth passes alongs genetic lines so does
friendship.

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agumonkey
what about emotional epigenetics ?

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jdmoreira
Having read "The Selfish Gene" I wasn't surprised. This study conclusion fits
pretty well within the general theme of the book.

If you haven't read it yet, I highly recommend it!

~~~
lentil_soup
Upvote for "The Selfish Gene". Should be mandatory for anyone interested in
science and/or biology! A great eye opener about how evolution really works.

~~~
jrs95
Definitely. And you shouldn't let the fact that it was written by Richard
Dawkins scare you off if you have a negative opinion of him -- it has very
little to do with his atheism.

~~~
nf05papsjfVbc
Also the subject of atheism should itself not scare you off. It is quite a
reasonable position to hold.

------
tosser350
People need to realize we are built on hardware that is hundreds of millions
of years old. We share a similar hormonal dominance hierarchy system with
fucking lobsters. You can't just say it's </CURRENT YEAR> and expect these
things to disappear. Tribalism was important for survival, trusting someone
who didn't look like you could mean death and thus was selected for over long
periods of time.

~~~
jawns
And then we became human and started not acting like lobsters.

We have intellects, a sense of morality, and a will. Those allow us to
drastically curtail what might otherwise be instinctive behaviors.

I know there are some determinists who say that free will is illusory and
we're as much slaves to our genetics and instincts as lobsters are.

But it certainly seems as if, in practice, tribalism (at least the clear-cut
type you're describing where we exclude people who don't look like us) is
recognizable and avoidable.

~~~
matkoboska
You are on a cocktail party. Have had a few drinks with friends. You all start
talking about spiders. How they are these wonderful tiny creatures to be
protected. You know, they got rid of insects and it's actually good to be
above this. After all we have intellects, a sense of morality, and a will.
We're not some freaking lobsters driven by phobias. And you know what? At this
wonderful evening party, we all agree, that this is just the case. And then we
all go home. Where, right after opening the door, you see this diguisting, big
spider crawling on the floor. Without thinking twice you crash it with your
shoe. And then -- using toilet paper perhaps -- pick up its remains and flush
it in the toilet. Just to be sure that the motherfucker is really dead. Not to
mention your 3 year old and 5 year old living in this house. And then, then,
you realize. What happened? Just talked about it an hour ago. And then I got
rid of this poor bastard anyway...

In a social setting, with people around having conversations, your brain
cortex fires off. It's spinning like crazy. And the cortex is all about logic.
It's all about intellect, a sense of morality, about a will, and group
hierarchy, and talking, and relaxation. You get the picture. When the phobia
kicks in... guess what... the first thing that will happen is that cortisol
will turn off your cortex. In the stressful situation, in fight or run
situation, your cortex is switched off brother. That's why this spider is
dead. That's why after 30 years of perfect marriage you might do stupid things
when 23 year old hot blonde is sexually provoking you. That's why live isn't
white and black. Even in 2017.

~~~
atapaiea
Or, like my father-in-law, you go and grab a paper towel, pick up the spider,
and let it go outside on front lawn. I have never seen him kill a spider. And
some percentage of the time, more and more with each passing year, even though
I am terrified of spiders, I don't kill them because of conversations like the
one you describe.

Just because some people react with their emotion doesn't mean everyone does
and it doesn't mean we have to.

~~~
csomar
This depends on your up-rising for the most part. When I was very young, there
was this spider that had its house below my small desk. I grew up accustomed
to these spiders and didn't allow my mother to clean them up.

Now, I don't fear spiders and also don't mind them as long as they don't wreak
the place with their filaments. I was surprised when a cousin of mine was
freaked out by one of them and wanted to insta-kill it.

Now if there is a bug... that's a whole different story. Even though,
logically thinking, these beasts are the same.

------
corporateslave2
What does this say about racism? Segregation?

~~~
cestith
The article specifically mentions olfactory similarities being pro-friend and
immune differences being pro-friend. It didn't mention ethnic markers like
melanin, face shape, nose width, ear size, or relative toe length at all. In
fact, it said they attempted to control for racial and ethnic differences. How
well that was accomplished wasn't really made clear in the article.

I can imagine that whether or not cilantro tastes like soap, whether or not
you love the smell of books, similar allergies, and if you can stand to eat
spicy foods goes a long way toward the likelihood of friendship. There are
bound to be social factors, geographic factors, and other factors. This study
is just pointing out that friends are likely to be more similar in certain
ways than people who aren't friends. Don't jump to too many conclusions on
just the summary article about the study.

------
pavement
Birds of a feather, no?

