Why can humans talk while chimps can't? The answer is more than just vocal cord anatomy; our brains have a lot to do with our ability to learn and use language. One 'language gene' is FOXP2. Mutations in FOXP2 lead to a rare but dramatic language disorder. Characterized by an inability to use grammar. We all know people who are grammatically challenged (stemming from illiteracy, for example), but this disorder is not the same thing - the affected people have a strong genetic barrier that prevents them using grammar, no matter how hard they work at it.

This disorder is a dramatic example of a language development disorder, but millions of children have much more mild language disorders. Many of these kids outgrow their language problems but not all. A group of researchers working in the UK and the US asked whether some of these relatively mild language disorders are somehow connected to the FOXP2 gene, which so far has only been found to be involved in dramatic speech disorders. Sure enough, they found that variants in a gene regulated by FOXP2 are strongly correlated with mild language disorders.