[hacst]

I recently read the book "Blueprint: How DNA Makes Us Who We Are" by Robert Plomin and it it was quite the eye opener as to how much the nature vs nurture debate seems to have been overtaken by genetic findings.

According to the book genetics seems to be the single biggest factor for a ton of things in our psychology. Including various measures of intelligence and achievement. As a layman the evidence presented seemed quite convincing. The book mostly refers to big studies with thousands of twins. To separate nature and nurture studies can do things like tracking twins given up shortly after birth into two different foster families who never had any contact to their birth parents later (correlated nature), track the development twins in the same family (correlated nurture) and so on.

According to Plomin the effects are huge (especially compared to what usually would be a significant result in a psychology study looking at nurture) and the controversial nature of such findings made the field extremely rigorous to the point where it is hard to imagine these results turning out to be wrong. Apparently it has all been replicated quite a bit by now.

To be honest I found the book quite shocking because it runs counter to so much that is "common knowledge" and "common sense". It basically mostly discards influenceable "nurture" as a defining influence at the population level. Once certain basics are met, relevant environmental influences are mostly too random to control and much of the rest is indirectly caused by "nature". "Nature" basically creates its preferred environment (called "nature of nurture" in the book).

As I am not in the field my ability to verify what the book says is limited. As far as I can tell Plomin is a very well regarded Psychologist and mostly know for his involvement in twin studies. If anyone in the field has better insight on how to evaluate what the book says I would be very interested.

[forapurpose]

Plomin himself seems to characterize it differently:

Another problem that Plomin encounters with explaining his findings is that people often confuse group and individual differences – or, to put it another way, the distinction between means and variances. Thus, the average height of northern European males has increased by more than 15cm in the past two centuries. That is obviously due to changes in environment. However, the variation in height between northern European males is down to genetics. The same applies to psychological traits.

“The causes of average differences,” he says, “aren’t necessarily related to causes of individual differences. So that’s why you can say heritability can be very high for a trait, but the average differences between groups – ethnic groups, gender – could be entirely environmental; for example, as a result of discrimination. The confusion between means and variances is a fundamental misunderstanding.”

https://www.theguardian.com/science/2018/sep/29/so-is-it-nat...

The above article, and Plomin, were discussed here:

https://news.ycombinator.com/item?id=18101570

[hacst]

That's what I tried to capture with the "at the population level" restriction. Plomin was quite clear that for the individual all bets are off so sorry if it sounded like the environment couldn't still screw you over (it definitely can). The part about inter-group differences is worth emphasizing and I should have done so.

That did not reduce my surprise about the things stated in the book though. If statements it contains like that after correcting for genetics "the most important environmental factors, such as our families and schools, account for less than 5 percent of the differences between us in our mental health or how well we did at school" and "Genetics accounts for 50 per cent of psychological differences, not just for mental health and school achievement, but for all psychological traits, from personality to mental abilities" are true, then I definitely consider that as going against "common knowledge" and "common sense". Definitely blew my mind.

Thanks for the links. Totally missed that it was discussed here before.

[SamReidHughes]

That doesn't address what the parent comment was talking about.