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A few additional studies lend credence to the idea that parenting matters:

- Kendler et al (2016) estimate large reductions in criminal offending using an adoption study w/co-sibling control (https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/criminal-offending-and-the-family-environment-swedish-national-highrisk-homereared-and-adoptedaway-cosibling-control-study/43B4EAE8189993694B50CB33F3AA9926)

- Holm et al (2023) use an RDD design to compare the test scores of Danish children whose parents divorce right after & right before the dates of national achievement tests. They estimate that divorce has an immediate -0.03 SD impact on test scores. (https://osf.io/preprints/socarxiv/p2qgk)

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one good point I haven't often seen brought up (education was untypically uniform, though it probably still is in most places IMO).

the rest isn't particularly well supported by the evidence. read up on protzko's work on fadeout before you put your money on childhood interventions (here's a hint from the review you cite "the majority of trials were not preregistered and did not have a study protocol of prespecified outcomes to assess whether selective outcome reporting bias or selective analysis reporting bias was present").

as soon as you leave aside the silly position "parenting doesn't matter" (don't know if anyone really believes it) and contend with the nuanced position "parenting doesn't matter as much as most think" or even "parenting among well-adjusted and well-nourished westerners explains a small portion of variance for most outcomes, but not e.g. years of education, so relax about all the inconsistent silly advice you're getting on everything from babywearing to multivitamins" there's much less of a gap to explain between twin study behavior genetics and the small effects found in RCTs and adoption studies.

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Counter conjecture: parenting (emotional care & socialization) matters, but parental "investment" (education & "prep") does not. Discourse about the former often devolve into arguing about the latter, as (a) genetics are a stronger constant to achievement than merit, (b) The Cult of Smart needs educational assistance "equal opportunity" to disguise oneself against scrutiny, (c) aristocratic education is only reserved for Old Money, (d) anything genetic correlate or direct parent is rhetorically reinterpreted as equivalent vices through "keeping it in the family". https://astralcodexten.substack.com/p/non-cognitive-skills-for-educational https://freddiedeboer.substack.com/p/education-doesnt-work https://erikhoel.substack.com/p/why-we-stopped-making-einsteins

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This post commits the Missing Effect Size fallacy, and it's a strawman. Shared environment typically accounts for 5-10% of the variance of a trait. Plomin doesn't deny this. You cite evidence like "Adopters made a difference in other ways too: for instance, mothers who drank were about 20% more likely to have an adoptive child who drank", but while you give us the tiny OR of 1.2, you fail to say how much the absolute difference in terms of overall variation is. For example, d here could be <0.10. You are hiding the fact that d is tiny to argue against a strawman that d=0.

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Nature or Nurture . . . . whatever . . .

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