[nunb]

I heard the most bizarre & unexpected opinion first-hand from an obgyn. Prior to this I was firmly in the nurture camp of nature/nurture, but this obgyn's opinion on adoptions shocked me out of my complacency.

I am hoping Sapolsky's latest book may shed some light on the subject without the Wade/Murray "bell curve" implications.

[decafninja]

Curious as to what you mean. I think you're implying that the personality makeup of the adopted child that comes from his/her biological parents is not to be underestimated? Is that really a questionable or controversial topic though?

The thought has occurred to me. I would describe both my wife and I as being stable mannered and not prone to rash decisions. Odds are a biological child of ours might resemble that personality.

I also acknowledge a child we adopt may have had biological parents with very different personalities than us, and therefore the child may be very different from us in personality.

At the same time, I don't believe that just because the child's biological parents might have been wild and crazy, the child is doomed to the same fate even with our care.

[d0100]

Some wild and crazy behavior comes by because of genetic "features" that translate into mental issues

But I do believe nurture can help to prevent or exacerbate those issues

[JamesBarney]

> At the same time, I don't believe that just because the child's biological parents might have been wild and crazy, the child is doomed to the same fate even with our care

Tell me you haven't read many behavioral genetics papers without telling me you haven't read many behavioral genetics papers :).

[pram]

After having kids, my opinion is they come out of the womb with baked-in personalities.

Not that we don't change as we age obviously, but it's definitely not a blank slate by a mile.

[random314]

What was the opinion?

[nunb]

adoptee turned to hard drugs (opiods) in his teens. the opinion was: what do you expect, the father was an addict too. at the time I was shocked as I was so firmly in the nurture camp.

[girvo]

Addiction, and specifically OUD is complicated, but there is real evidence that genetics plays a sizeable role in the physiological dependence side of it.

However the main risk factor for trying and then abusing opioids, for example, is trauma, typically but not only in childhood. Basically, it’s both nature and nurture, as most things are. Where the percentages lie for both, I don’t think we know yet.

[JamesBarney]

Trauma is deeply intertwined with genetics.

For instance parents who have genes that increase impulsivity are more likely to e beat their kids exposing them to trauma, the kids are more likely to do dumb things that expose themselves to trauma, and the kids are more likely to do impulsive things like try drugs.

So it's hard to disentangle what portion of the effects of trauma are direct and which are confounds.

[girvo]

Oh yeah, definitely. It's a complicated mess of variables, that I don't even know how one would begin to tease them apart, but that's also why I firmly come down on the side of "it's both" -- as not all trauma is directly from biological parents, for example.

[nunb]

yes, I agree with you. It's just at the time I was unaware that brain chemistry could be genetically dependent; although as you say that's pre-disposition, and the trigger can be trauma, and sometimes knowing you are adopted can be the source of that trauma, thus triggering the behaviour.

[tfigment]

I can only speak from personal experience but that is what happened to my family. My brother is a sociopath who caused our family a lifetime of difficulty. The biological mother was drug addict and abusive before adoption and he became an addict. My sister also adopted from different family was less of a problem but also had some issues. My dad was very kind and not abusive and spent way too much trying to help. Who knows maybe it was environment and early abuse or something but nature stacked the deck I think in my family. The other issue with adoption is limited access to family medical history.

[rayiner]

Do you really think genetics don't matter? Depending on the study, IQ heritability is between 60-80%.

[random314]

Heritability includes both nurture and nature(genetic). There is no real way to separate nature and nurture in these studies.

For eg, if you take Einstein's kid and let wolves raise him, we can expect the kids IQ to be somewhat lower.

I would guess IQ is primarily genetic, but these heritability studies don't show that.

[random314]

Just found this very rare and valuable data point.

https://www.newsweek.com/identical-twins-raised-apart-differ...

There was a 16 point IQ difference between twins. Nurture had a strong impact on IQ in this case.

[tptacek]

This isn't even wrong.

Is the number of human toes genetic? How heritable is the number of toes on a human being?

Is wearing a dress genetic? How heritable is whether or not you wear a dress?

[rayiner]

I don’t really understand your argument. Wearing dresses isn’t heritable, we know that because most women’s grandmothers wore dresses and most women wear jeans or casual wear.

Heritability isn’t proof that a trait is genetic, but it’s strong evidence once you start addressing confounding factors. As I recall, the IQ heritability research was done with twin studies.

This is like shocking to me we’re even debating this. I would have assumed it’s conventional wisdom.

[tptacek]

Wearing dresses is heritable! Heritability is simply the ratio of genetically-caused variation to total variation for some trait across a population. Bad driving is heritable. So is risk aversion. So is musical taste. So is how much TV you watch. All of these: studied.

Traits can trivially be minimally heritable and totally genetically determined. The number of fingers on your hands is genetically determined by your Hox genes. But the variation in the number of fingers on your hand (more precisely: across the population) is overwhelmingly not genetically determined. Genetically determined, low heritability.

Traits can trivially be maximally heritable and not at all genetically determined. Whether or not you wear lipstick is largely decided by XY vs. XX. But there's no gene for wearing lipstick; if the cultural ball had broken a different way, we might all be wearing lipstick, or none of us. Genetically unencumbered, high heritability.

So: you haven't said anything. You're not even wrong. All you pointed out was that you can do a study and determine that population variations in intelligence (or bad driving, or social trust, or fear of dentists) are traceable to genetic variance. That doesn't mean that genes literally encode the outcome.

Heritability isn't "strong evidence". It's barely evidence at all. It's literally just a framing of the question, which your argument simply begs. Irresponsibly, at that. None of this should be news to you.

I don't even have to take a position on the blighted question of whether intelligence is genetically determined (or whether we can measure it meaningfully at all, or whether it's fixed at birth or fluid, or whether outcomes in intellectual performance are epigenetic). And I'm not. I'm just pointing out that your argument, the one I replied to, was literally vacuous.

[random314]

> As I recall, the IQ heritability research was done with twin studies.

No, it wasn't. Such a set up is impossible because of lack of samples and sampling bias.

All that "IQ is X% heritable" means is that they ran a linear regression on a large data set and saw that the variance error in the regression reduced by X% when they plugged in parental IQ as a covariate in the regression.

This is a correlational study as causal studies are impossible. Correlational studies are inherently spurious and ignore lots of confounding factors. Nevertheless, we can say that what we routinely observe in real life - smart parents having smart kids, has been grounded in real data.

For getting effect of race on IQ you plug in race as a covariate. Typically, most of the race based IQ research remove parental IQ as a covariate. All of these regression based studies are dubious and there is no real way to correct it. A large data set of twins who were separated at birth could help, but there are caveats there as well.

As an aside, Jordan Peterson seems to love these race IQ regression models and likes to call them hard undeniable science. He immediately switched sides when talking about climate models and how these models can't be trusted, because the simple choice of covariate included creates absolutely unreliable and biased models.

[imtringued]

Okay but that just implies that having a wide distribution of IQ is well adapted to our natural environment.

[rayiner]

In the same sense as humans having a range of strength and speed is well adapted, sure. But athletics also tends to run in families.

[tptacek]

We have relatively strong evidence for a significant degree of genetic determinism in athletic ability (at least for some sports). We do not for intelligence.