Revising the Bell Curve
Related to intelligence is IQ, the heritability of which is 45% for children, and rises to 75% for late adolescents and adults. IQ is related to g-factor, which includes subsets of mental abilities related to fluid intelligence (Gf), crystallized intelligence (Gc), visuospatial processing (Gv), working memory (Gwm), and quantitative reasoning (Gq). A detailed meta-analysis of intelligence involving 78,308 individuals, looking for associations between intelligence and specific genes identified 336 associated SNPs in 18 genomic loci, of which 15 were new. It confirmed 40 novel genes for intelligence. The identified genes were predominantly found in brain tissue. Overall the SNPs accounted for a non-negligible 5.0% difference in intelligence.