Pretty interesting, and I have long suspected this, or actually worried about it, because I’m opposed to the hereditarian line. However, you can’t have Flynn Effects raising IQ’s by 3 points via genetics, so the Flynn Effect shows that environment can also play a strong role in, at the very least, increasing IQ scores.
For those who don’t want to click the link, the article states that UCLA researchers have found evidence that intelligence is largely inherited. That’s overstating the case of what they found, though. What they found was identical twins had very similar levels of myelin sheathing in the brain’s axons in brain regions key to intelligence, such as the corpus callosum and the parietal lobes.
Myelin is a coating on axons, which are the connections between neurons, or brain cells. The fatter the sheathing, the better the axons work, that is, the faster the axons fire messages. Myelination of the brain actually peaks in middle age, which is not really evidence that this process is intimately linked to intelligence, since fluid IQ (a measure of pure, raw brain speed) peaks around age 23 and then drops. Crystallized IQ often keeps going up into middle age and beyond.