Believe in Racehorse Theory

In Pres. Trump's speech, he mentioned "if you believe in the racehorse theory", then Elon Musk's son will be smart.

He said something similar in 2020, according to Rolling Stone magazine:

It doesn’t take a secret decoder ring to understand what Trump was aiming at in Bemidji. The idea that white Minnesotans, like racehorses, have superior, inheritable genes is white supremacy — embraced not as a cultural construct, but as if it were based in hard science. In another moment, Trump’s remarks would have made for a front-page scandal. But on Friday, as America reeled from the death of a feminist icon whose departure threatens to accelerate a generation-long right-wing takeover of America’s highest court, as well as from a death toll in the coronavirus pandemic that has surpassed 200,000, the president’s open embrace of eugenics hardly sparked notice.

But it is time to wake up to the threat before us: We have an aspiring authoritarian president who romanticizes martial law and dreams of locking up his political opponents. Trump does not recoil from the most dangerous ideology of the 20th century, but instead celebrates it on the campaign trail in increasingly explicit terms. These may be dark times in America. But if Trump is not stopped at the ballot box in November, our democracy is in plain danger of fading to black.

Some professors argue:

This insidious idea has provided the foundation for some of the most unjust, repressive, and inhumane regimes in human history. This is why it matters.

The professors do not give any evidence that the theory is wrong. Unly that is leads to uncomfortable ideas.

Here is the scientific data

Whether differences in intelligence are due to people’s different genes or to their different environments has long been contentious. One answer to this question comes from twin studies and adoption studies. By comparing outcomes for identical twins (who share all their genes) with those of fraternal twins and with unrelated children, one can deduce the relative influences of genes in comparison with “shared environment” (all environmental factors shared by siblings growing up together) and un-shared environment (everything else, which can include things like randomness in embryonic development). Such studies give high estimates for the genetic contribution to differences in intelligence, such that the heritability of IQ is typically estimated as around 70%.

A different method is to look directly at genes, through Genome Wide Association Studies (GWAS), which sample large numbers of genes in large numbers of people, attempting to measure and add up the affect of each gene on IQ. This typically gives much lower estimates for the effect of genes, and the marked difference between estimates from twin studies and those from GWAS studies is referred to as the “missing heritability” problem.

The article goes on to explain that there are a large number of genes with small effects. They might have to sample 100 million people with genetic and IQ tests to get accurate estimates on what specific genes are contributing to intelligence. For now, we just know that there is an overall heritibility.