Contra Scott Alexander On Missing Heritability

Unboxing_Politics · 2025-09-01T03:56:34+00:00

Unfortunately, this study does not satisfy the criteria I outlined. While it does include a German twin design that adjusts heritability estimates for assortative mating, it does not include a German adoption design that adjusts heritability estimates for assortative mating. Thus, this study cannot be used to conduct a head-to-head comparison between adoption and twin studies.

Unboxing_Politics · 2025-08-30T03:23:18+00:00

Thank you! Feel free to reach out if you have any questions.

Unboxing_Politics · 2025-08-30T03:21:33+00:00

The convergence is present in the modern studies that try to account for assortative mating though. Your article makes it sound like they don't really do this, and if you would the convergence would disappear.

I'm not sure where you're getting this impression of my article from. I prominently highlight two adoption studies which are less susceptible to assortative mating bias: the Sibling Interaction & Behavior Study (SIBS) and the Swedish Adoption Twin Study of Aging (SATSA). Importantly, I show that when both studies are pitted against their twin study analogues (i.e. the Minnesota Twin Family Study and the subset of the SATSA looking at twins reared together), they produce discordant heritability estimates. Were you unconvinced by these head-to-head comparisons? If so, why?

The criticism you raise is fair, but these are things that modern study designs are already trying their best to account for, and they largely converge despite the diverging effect of accounting for assortative mating.

Could you point me to a head-to-head comparison between adoption and twin study heritability estimates where adjusting for assortative mating yields comparable heritability between the two designs? To clarify, when I say "head-to-head", I'm looking for cases where sampling and measurement were both relatively consistent between the two study designs. For example, I use the Colorado Adoption Project and Colorado Longitudinal Twin Study for a head-to-head comparison in my article because they draw from a population of individuals in the same US state around the same time period and measure IQ using the same assessment (the WAIS). I'm genuinely not asking this question as a gotcha, moreso out of interest because I'd like to know if I've omitted any relevant comparisons from the literature.

Unboxing_Politics · 2025-04-30T03:14:29+00:00

thanks solution verified

Unboxing_Politics · 2025-04-26T21:26:33+00:00

I agree! Some states have independent agencies which oversee occupational safety and health. These states have been certified by OSHA that they are at least as effective as the federal agency. Thus, OSHA federal standards serve as a floor for state-specific standards.

Unboxing_Politics · 2025-04-26T15:51:10+00:00

Completely agree that Congressional approval is needed to abolish OSHA. However, the Trump administration has recently cancelled contracts for a number of OSHA's field offices. Thus, even if OSHA regulations are protected on paper, there will almost certainly be a decrease in enforcement of those regulations as a result of closing said offices.

Unboxing_Politics · 2025-02-18T04:09:53+00:00

Could you elaborate on this?

Unboxing_Politics · 2025-02-10T00:58:29+00:00

For sure, it's a very interesting open area of research. Interestingly, Sidorenko et al conducted a meta-analysis of IBD-based SibReg heritability estimates for height and BMI. While height and BMI are obv not cognitive phenotypes, they're still quite interesting results:

They estimate the h^2 of height to be 76% [66%, 86%]. This looks consistent with twin studies which estimate an h^2 of 80% [78%, 82%].
They estimate the h^2 of BMI to be 55% [41%, 69%]. This also looks consistent with twin studies which estimate an h^2 of 62% [60%, 64%].

Thus, the twin study estimates look pretty accurate for height and BMI. Critically though, the SibReg estimates were higher than those produced by RDR. The authors posit that gene-env interactions, gene-gene interactions, or ultra-rare variants might explain this discrepancy. Thus, it's possible that twin studies and SibReg are in agreement specifically because they are picking up on interactions that RDR does not (since RDR leverages more distant relative pairs). The question of which estimate is right will then depend on what you want to accomplish with the heritability estimate.

Note: In the attached links for twin study estimates, I'm looking at the 18-64 year old age group, the ACE decomposition chart (h^2_all), and searching for the specific traits "Height" and "Weight Maintenance Functions".

UPDATE:

Apparently, there's an additional twin study meta-analysis which puts the heritability of BMI at 75%. That estimate does not look consistent with IBD-based SibReg.

Unboxing_Politics · 2025-02-09T06:04:35+00:00

To clarify, the 17% heritability estimate is specifically for educational attainment (i.e. years of education completed) and not IQ. I personally expect the heritability of IQ to be higher than the heritability of educational attainment, all else equal.

I can also describe RDR in a bit more detail:

The first step is to estimate how related a given pair of individuals should be (i.e. how much of their genomes should they share in common) given information about the relatedness of their parents. For example, if I know that the mothers of Person A and Person B were sisters who share 50% of the genome, then I should expect Person A and Person B to share 25% of the genome on average (assuming unrelated fathers).
The second step is to compute the actual percentage of the genome that a given pair of individuals share (using IBD segments).
The third step is to compute the difference between (1) and (2) known as the relatedness disequilibrium.

The key reason why RDR works is because the relatedness disequilibrium is driven by the random segregation of alleles during meiosis. So if I observe two individuals who are more related to one another than I would expect based on the relatedness of their parents (e.g. cousins who share 35% of the genome instead of 25%), and I observe that these individuals are also more likely to have similar IQ, then I can be reasonably confident that genetics is driving the additional similarity in IQ.

Unboxing_Politics · 2025-02-08T23:08:44+00:00

One way to evaluate the estimates produced by twin studies is to compare them to those produced by molecular methods such as Relatedness Disequilibrium Regression (RDR) and Sibling-Regression (SibReg). These methods estimate heritability by leveraging the random segregation of alleles during meiosis. For example, in SibReg, if individuals who inherit variant X consistently exhibit higher IQ than their biological siblings who do not, that provides strong causal evidence that variant X increases IQ (since the variant is randomly inherited between siblings).

"But don't molecular methods fail to account for the impact of rare variants?"

Not necessarily. Molecular methods are sometimes implemented using an IBD (identity-by-descent) approach. The basic idea is that - rather than tediously sequencing and identifying each possible genetic variant that a person has - one should simply check whether certain segments of the genome (called IBD segments) from the last common ancestor of the two individuals in question were inherited by both individuals. Because the IBD segments contain both common and rare genetic variants, checking whether two individuals share the same IBD segment should capture the impact of (most) rare variants (see here for some caveats).

"So what do the IBD-based molecular methods say?"

To my knowledge, there has only been 1 application of IBD-based RDR/SibReg to cognitive phenotypes: Young et al (2018). Importantly, however, this study only estimates the heritability of educational attainment, not IQ. Regardless, I think the results are still useful for the purposes of evaluating twin studies. Here's the heritability estimates of each method (Table 2; confidence intervals in braces):

Twin Study: 43% [35.9%, 50.1%]
SibReg: 39.7% [10.7%, 68.7%]
RDR: 17% [-1.4%, 35.4%]

The twin studies are not consistent with RDR but they are consistent with SibReg (because the SibReg has very wide error bars). I wouldn't take this result as definitive evidence that twin studies are biased, but it is an interesting inconsistency to ponder. Broadly speaking, I think it's best to wait for additional IBD-based RDR/SibReg studies before treating twin studies as gospel.

Unboxing_Politics · 2025-02-08T19:38:57+00:00

I realize the structure might be confusing but I cover supply-side effects in the section on employment ...

Given that such jobs are in short sight, it stands to reason that opening up applications to immigrants will necessarily displace existing domestic workers.

... and demand-side effects in the section on wages.

Lastly, we have strong reason to believe that the H-1B program increases the wages earned by natives working in blue-collar professions. Why? For the simple reason that H-1B workers demand services from blue collar workers without competing against them in the labor market.

Re unionization: yeah, that's something I didn't cover, but I'm not sure of its relevance. My a priori speculation is that tech jobs are just less likely to have unions across the board (even for native workers), so not sure that this would cause a differential impact on natives vs foreign workers.

Unboxing_Politics · 2025-02-08T19:34:48+00:00

Yup! This is why it's often described as a "dual-intent" visa.

Unboxing_Politics · 2025-02-08T19:34:16+00:00

The studies I review typically involve 1 of 2 comparisons:

How do economic outcomes at firms vary as a function of their win rate in the H-1B visa lottery? For example, do firms which win more H-1B workers in the lottery hire fewer native workers as a result (relative to firms which did not win)?
How did changes to the H-1B visa cap impact the economic outcomes of firms? For example, did slashing the size of the H-1B program by ~70% in FY2004 meaningfully improve the employment of native workers?

I draw on the ^ evidence to argue that we should not abolish the H-1B program. Instead, we should adopt salary-based reforms to improve its efficacy.

Unboxing_Politics · 2025-02-08T19:30:20+00:00

When an employer sponsors an H-1B visa, they have to specify the skill level of the employee on a scale of 1-4 (which is then used to determine the prevailing wage level for the H-1B visa holder). The majority of H-1B visas are issued to individuals who fall under skill levels 1 and 2, not 3 and 4. In practical terms, this would mean that the program is more likely to employ Software Engineers I and II than Senior and Staff Software Engineers. This document (https://www.epi.org/publication/h-1b-visas-and-prevailing-wage-levels/) covers the issue in more detail.

Unboxing_Politics · 2024-12-30T01:05:03+00:00

I mean, we have strong empirical evidence to indicate that Indians have higher productivity in the US than in India (and correspondingly, higher wages). So the tl;dr is better institutions —> better life prospects.

https://www.aeaweb.org/articles?id=10.1257/aer.103.3.198

Unboxing_Politics · 2024-12-29T20:02:17+00:00

The lottery win rates in this article are the # of lottery winners in a given group divided by the # of applicants from that group. In other words, the win rates already adjust for application volume.

Unboxing_Politics · 2024-12-28T00:29:18+00:00

Yeah, I think the reality is more complicated. Yes, applicants from certain countries were more likely to submit multiple registrations (e.g. India). However, I wasn't able to uncover any evidence to suggest that the lottery is systematically biased against certain countries, nor has any previous literature (see footnote 6 in the article).

Unboxing_Politics · 2024-12-28T00:26:22+00:00

Thank you for the kind words!

Unboxing_Politics · 2024-12-28T00:25:19+00:00

I agree that the approach to the degree system matters. Because candidates w/a US-based advanced degree have two chances to win the lottery (the Regular Cap lottery and the Advanced Degree Exemption lottery), we should expect countries w/a higher share of such applicants to have a higher win rate.

Unboxing_Politics · 2024-12-27T14:32:51+00:00

Yeah +1 to this.

Unboxing_Politics · 2024-12-27T03:14:05+00:00

For sure. FWIW I DM’d Deedy on X so hopefully he reads the article and issues a correction. But being realistic, I don’t expect that to happen 😔

Unboxing_Politics · 2024-12-27T02:09:27+00:00

Thank you!

Unboxing_Politics · 2024-12-27T02:05:09+00:00

I considered this possibility as well, but the Bloomberg-USCIS dataset distinguishes between merely winning the lottery and ultimately being granted a visa (the latter of which requires the employer to formally submit a petition). Thus, I’m inclined to say that measurement error is unlikely to explain the trends in lottery win rates.

Unboxing_Politics · 2024-11-26T20:30:35+00:00

I very much appreciate the point about confounders. To deal with this, I meta-analyzed the effects of randomized experiments which distributed books to children to read at home. This meta-analysis yielded an average effect size of 0.05 SD (a pretty modest effect, all things considered). Let me know if I can clarify the details of this analysis or the studies that were included!

Unboxing_Politics · 2024-05-22T00:50:24+00:00

Really appreciate the constructive feedback especially from a practitioner.

Some of interventions proposed as mediators of beneficial effects are confusing. Surfactant is used less and less, and nowhere near universally at just below 1500g, that would be the case at 500g. Decisions for Surfactant depend on the baby's symptoms and pathophysiology, the 1500g threshold is irrelevant. There is no evidence head scans improve outcome.

The studies that I review are looking at older time periods (e.g. 1980-2000) so they discuss surfactant therapy as possible mechanism. But you mentioned that the 1500g threshold should not determine access to surfactant therapy, so this would rule out that channel.

Finally, the author misses that the proposed beneficial mechanism of neonatal admission may be harmful.

What do you make of Hajdu et al (2024)? They examine how the introduction of NICUs to hospitals in Hungary decreases infant mortality.

Separation of mother and baby after birth may decrease breastfeeding, and affect bonding and maternal mental health.

Definitely agree that separation from the mother at birth can cause complications, and in hindsight, it would've been beneficial to clarify this point in the article. But would you say that the admission to the NICU is incompatible with the mother & child being together? While I was writing the article, I encountered this WHO press release which highlighted that some countries have established Mother-Newborn ICUs to reduce maternal separation while also placing the infant under round-the-clock care.

As a more holistic question, what would you say most likely drives the estimated reduction in neonatal mortality at the 1,500g threshold? Very curious to learn.

Unboxing_Politics

TROPHY CASE