The study is a fascinating one, using thousands of brain scans and hundreds of thousands of sequenced genomes to look for associations between genes, brains and hands. It found that, in left-handers, the left and right hemispheres had stronger links in the regions associated with language, which could correlate with greater language ability.
It also found “significant positive correlation” between left-handedness and mental health outcomes such as sensitivity, having “fed-up feelings” and being a “worrier”. Look, I’m no scientist, but that feels extremely real.
Left-handedness runs in families and identical twins are more likely to have the same hand dominant than are fraternal twins and siblings. This implies that the genes do have some influence, but are not the whole story. Previous studies have suggested left-handedness is about 25% heritable, with the other 75% of the variation accounted for by environmental factors – although what those factors are remains elusive.
No, I am not about to insist that I know what causes sinister. Rather, just to make a point about genes.
Yes, inheritable. Sometimes, often, whatever. The trait at least might be inherited, and different ones more strongly or weakly.
But that doesn’t mean that something that you parents don’t have is therefore environmental in cause. For there is always that random mutation in each and every generation, isn’t there?
We thus have three – inherit, rising anew through genes/chromosomes/whatever in this generation and environmental causes.