Gene studies of intelligence these days are mind-blowing. There's a new one practically every week. This new one is a meta-analysis of 14 studies of whites that totals 270,000 individuals.
The researchers examine the link between 9.2 million gene variants and IQ. Turns out that it's difficult to detect the impact of a single gene because most traits--and intelligence is no exception--are caused by hundreds if not thousands of genes. The authors found that between 139 and 1,016 genes influence IQ, depending how strict the method used. Collectively, all the single points that varied (single nucleotide polymorphisms or SNPs) and were found to matter explained around 20% of the variation in intelligence. That number will likely go up as studies get more powerful.
Further analysis revealed that the relevant genes are linked to how the brain develops and functions: neurogenesis, neuron differentiation, regulation of nervous system development, regulation of synapse structure and activity. Being smart simply means you've got a brain that works really well.
The authors also found that the genes that explain IQ also increase longevity and lower one's risk of Alzheimer's, schizophrenia, and ADHD. The picture emerging is that some people are lucky and have genes that lead to a wide range of healthy outcomes, while the unlucky ones might suffer from a range of problems. The only exception reported in the study was autism: IQ genes were linked to more autism.
A bi-directional relationship was found for IQ and educational attainment; while IQ led to more schooling, more school also boosted IQ.
Since our culture creates unrealistic expectations by telling us, "You can be whatever you want," one goal of this blog is to inject a little adulthood with Clint Eastwood's, "A man must know his limitations." There is wisdom in the view that you do have some say in your life, but where you end up is partly beyond your control. At the risk of sounding like a liberal, go easy on yourself and others.