Being a leftie has a genetic component, is linked to better verbal skills and is associated with a lower risk of Parkinson’s disease, according to a new study published in the journal Brain. Unfortunately for Guardian readers, that’s leftie in the handedness sense, not political. Fortunately for me, I’m both.
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.
Talking “as a leftie” always feels like an odd identity to adopt. It’s something I share with about 10% of the population, which is a fairly large community to claim is special and different. That said, it is not much bigger than the cohort of any given star sign, and that hasn’t stopped astrology folk.
And unlike being a Saggitarius, being left-handed has had a concrete effect on my life. That has always been the case with using scissors (painful) and pens (smudged) and playing musical instruments (confusing) and racquet sports (I’m extremely bad at them, although also extremely bad at non-racquet sports, so that might have nothing to do with my handedness).
It looks like it might also be the case for some of the more deep-seated aspects of my personality, health and general phenotype. Which is great, and gives me just a little bit more justification when shouting at lecture theatres that have those stupid flip-down desks, or user interfaces that assume I’m holding a stylus in my right hand. I am special! Mum always said it, but now the scientists have proved it.
