Twins reared apart do not exist
Scope of the Article and Thread
- Commenters stress the article is not arguing “genes don’t matter,” but that evidence for very high IQ heritability from “twins reared apart” is weak because:
- True rearing-apart cases are extremely rare.
- Key studies (e.g., Minnesota twins work) assumed independent environments that likely weren’t independent.
- Important data (e.g., on non-identical twins) were omitted or under-emphasized, making strong claims unwarranted.
How Heritable Is IQ?
- One camp cites traditional twin estimates of ~50–80% heritability.
- Others argue there is “definitely not” consensus on this:
- Genome-wide association studies find only ~10–30% heritability from common variants.
- This gap is the “missing heritability” problem; debate over whether rare variants can close it.
- Several people emphasize that even 50% heritability yields only modest correlations; genes influence IQ but don’t fix outcomes.
Genes vs Environment, and Misuse of Results
- Repeated insistence that heritability ≠ determinism: genetic potential, environment, and chance all matter.
- Some say the core problem is not the studies but how people use them—to justify class, race, or wealth hierarchies and “socially self‑serving conclusions.”
- Others argue personal observation (children, animal breeding) shows strong genetic influence on personality and cognition, and see skepticism as ideological.
IQ, Success, and Meritocracy
- Multiple comments link enthusiasm for IQ heritability to:
- Successful people wanting to see their status as deserved, inevitable, and guilt‑free.
- High‑test‑scorers using IQ as an identity marker despite limited real‑world success.
- Pushback: one can acknowledge luck and circumstance without rejecting heritability.
- Broader meritocracy debate:
- Some see “meritocracy” as a moral cover for extreme inequality.
- Others distinguish neutral market pricing from moral “reward” and note misalignment between pay and social value.
Measurement and Cultural Bias
- IQ tests criticized as heavily influenced by language and cultural exposure, especially vocabulary.
- Education, family attitudes toward learning, and broader environment are seen as tightly intertwined with measured IQ, complicating genetic inferences.
Blank Slate and Political Framing
- Several commenters object to “blank slate” strawman accusations; most accept some heritability but dispute its magnitude and social meaning.
- There is meta‑discussion about bias in social science, ideological pressures on controversial topics, and whether egalitarian beliefs themselves serve a social function.