Summary of the Bet on Genetics and Intelligence

The article declares the author the winner of a bet made in 2018 with political scientist Charles Murray, co-author of the controversial 1994 book The Bell Curve.

The Bell Curve and Murray’s Wager

Core Claims of The Bell Curve:

Intelligence (measured by IQ) is a crucial factor for success.

A person’s intelligence is substantially determined by genetics.

Controversially, the authors entertained the possibility that socioeconomic and educational differences among racial groups are partially attributable to genetic differences in IQ.

The Bet’s Premise (2018): Murray wagered that by 2025, “we will understand IQ genetically” and that “most of the picture will have been filled in.”

The Author’s Conclusion in 2025

Result: The author claims victory, arguing that the scientific goal of understanding the genetic causes of intelligence has receded, not advanced. (Murray insists he won and plans to publish his rebuttal.)

Current Status: As of 2025, scientists “do not remotely understand” the genetic or brain mechanisms that cause differences in intelligence.

Scientific Progress on IQ Genetics

The article tracks the evolution of genetic research, arguing that no single method has provided the deterministic explanation Murray anticipated:

Twin Studies:

Established that intelligence is “heritable” in a limited statistical sense (identical twins are more similar in IQ than fraternal twins).

The authors of The Bell Curve interpreted this as strong evidence of genetic transmission, despite the measure being difficult to interpret and not providing biological insight.

Post-Human Genome Project:

Initial, direct searches for individual “IQ genes” were unsuccessful, with reports repeatedly failing to replicate.

No single gene is known to increase intelligence (only genes causing profound mental disabilities).

Genome-Wide Association Studies (GWAS):

This technology scans the entire genome (SNPs) for associations with behaviors.

While many tiny, statistically significant associations with intelligence were found, the cumulative effect has “leveled off.”

The resulting estimates of heritability are only about a third of those based on twin studies.

The associations do not add up to a neurogenetic explanation.

Controlling for Environment: Studies comparing siblings show that the direct effects of DNA on IQ look “even smaller,” as some SNP associations may be indirect (e.g., associated with wealth/socioeconomic factors, not direct biology).

Final Argument

IQ, like financial solvency, is only modestly correlated with genetic differences and is “highly malleable and responsive to a person’s environment.”

Murray’s prediction required a “settled genetic explanation” because, without one, IQ cannot play the deterministic role The Bell Curve requires.

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