Is IQ just measuring how rich your parents were or does it capture something real beyond socioeconomic background?
Every time IQ comes up someone says the tests are just measuring privilege and access to resources. The argument is that kids from wealthier families score higher because they have better schools, more books, better nutrition, and more test prep, not because they are actually smarter. I want to know what the research actually says. Does SES explain IQ differences or does IQ have predictive power that is independent of socioeconomic background?
SES and IQ correlate but causation runs both ways. Smarter parents earn more and pass on both genes and environment to their kids. Within family studies that control for shared background still find strong genetic effects on cognitive ability, and polygenic score research shows DNA variants predict IQ outcomes even after controlling for parental income and education. If IQ were purely a product of privilege it would stop predicting outcomes once you controlled for SES. It does not.
The cleaner test is whether IQ predicts outcomes independently of SES. It does, consistently, across decades of research. That is hard to explain if it is just measuring background advantage.