In a paper posted to BioRxiv, researchers from the University of Edinburgh report that they genotyped some 20,000 people from the Generation Scotland family cohort to tease out the effects of gene variants on intelligence, extraversion, and neuroticism. As the cohort includes family members, the researchers could delve into variants not typically found in genome-wide association studies of unrelated people.
Because of this, the Edinburgh team says it was able to capture the full amount of heritability of intelligence and education that had been estimated through twin and other studies.
"If the result stands up, they've solved the missing heritability problem for intelligence," Steve Stewart-Williams from the University of Nottingham Malaysia Campus, who was not part of the study, tells New Scientist, calling it "[p]retty impressive."
In particular, New Scientist says that CNVs, structural variants, and rare variants seem to affect intelligence. As rare variants are more likely to be harmful, New Scientist says it appears that a person's intelligence might be in part due to their mutational load.