Your post should be submitted here too: https://news.ycombinator.com/item?id=10545689

Heritability is a relative measurement. You need to know what environmental factors you are controlling for in order to measure it. Because we live in societies that are highly stratified based on attributes that are genetically linked there can be environmental effects on intelligence that are difficult or impossible to correct for that create a correlation between genetics and intelligence.

Native language is an almost perfectly heritable trait, but that does not imply it is genetic.

(However, it is true that saying that genes contribute to intelligence isn't eugenics. Eugenics is a methodology where you attempt to selectively breed humankind by broader intent, rather than by emergent properties of human tendencies. A proposed trait to optimize is often intelligence, but similarly frequently it's attractiveness and things like that. Genetic influence on intelligence is simply a hypothesis whose testing would have consequences on the practice of eugenics.)

------- edit ------- I see your reply to the other comment. I think a quote from the article that makes your point far better is "[...] studies have consistently shown that genetic influence on individual differences in intelligence is substantial." I negligently assumed you were specifically talking about heritability.