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Left-handed DNA found

Anything Left-Handed Research
Research

- and it changes your brain structure!

Left handed DNA foundResearchers have studied the full DNA sequences of 38,000 left-handers from a total of 400,000 people on the UK Biobank records to see if they could spot any consistent differences related to their left-handedness.
 
They found four "hotspots" where there seemed to be genetic differences that could be of interest. These included evidence that the two halves of the brain - the left and right hemispheres - were better connected and more co-ordinated in regions involved in language for the lefthanders, possible resulting in better language skills. The study also indicated slightly higher risks of schizophrenia and slightly lower risks of Parkinson's disease in left-handed people.
 
This all by no means conclusive, but it is a big first step to establishing the genetic basis for left-handedness. But the best guess at the moment is that handedness is 25% genetic and 75% down to the environment (anything that's not in the genes, including the environment in the wormb). This study has found only the first 1% of that genetic component and only in a British population, so there is a long way to go!
 
[Updated August 2026] Since this study, an even larger genetic analysis of over 1.7 million people (Cuellar-Partida et al., 2021, Nature Human Behaviour) has confirmed the broad picture: no single "left-handed gene," but dozens of small genetic contributions working together, alongside a strong role for environment and chance in early development. Our estimate above that handedness is roughly a quarter genetic lines up well with twin studies (e.g. Medland et al., 2009, ~24% heritability) — interestingly, the more recent gene-by-gene studies so far only account for a modest slice of that, meaning most of the specific genetic contributors are still unidentified. See our detailed article on the genetics of left-handedness for the fuller picture →
RTE in Ireland produced a short video on it with an interview with one of the researchers, Professor Gwen Douaud, who is herself left-handed.
 
If you fancy some heavy reading, the study results were originally published here:

How do you write a letter X?

Synesthesia and left-handedness

Are there lots of left-handers in your family?

Comments 14

  1. Rachel
    I have been the only left handed person in my entire family on both sides my whole life until my nephew who was born 7 years ago came along and no one on his dad's side of the family is left handed. His mother is my sister so maybe genetically he got it from me but where did I get it from?? My mother did research a few years ago on our family tree so I asked her to see if anyone else was left handed and she didn't find a single person going back several generations. It's gotta start somewhere so I guess that's me.
  2. Nostradamus
    For millennia in the world, and even today in some countries, left-handers are seen as something diabolic, related to Satan. Even day they are despised in some cultures.
    1. Nostradamus
      Correction: Even today
  3. Alicia M.
    ~ Follow-up: Though I'm American, in my research, I also found that I have British, English and Native American ancestry. My ancestors on my father's side were from Liverpool, England and my maiden name is a popular one in Cornwall. My mum's side is Irish and Spanish. This is why you can't put people in boxes! ~
  4. Alicia M.
    ~ I agree it is genetic, it's in my DNA. What's so great about being right-handed? You're just like everyone else, while being a southpaw makes us unique. Parents: when you see your child/children using their left hand at an early age, STOP DISCOURAGING THEM. It only serves to exacerbate what comes naturally, esp. when it's inherited. I also have shoulder-length natural curly hair and that also makes me unique. Why would I want to be like anyone else when I enjoy being who I am? ~
  5. Nostradamus
    I think it is 100% genetic.
    1. Alicia M.
      ~ The winter of 2017, my husband and I went ice skating. Attempting to finish the last lap before the rink closed, my right arm went backwards, my legs and skates went out from underneath me. Disoriented, I got up and saw my right wrist swelling. An orthopedic doctor X-rayed it, put a cast on it and told me to take it easy (it turned out to be a hairline fracture). That's when I knew I had to do EVERYTHING WITH MY LEFT HAND. In the late 70s/early 80s, I studied my ancestry, only to find the left-handed gene is on my father's side of the family. So much for him trying to discourage me from using my left hand. As the oldest of 5 kids, both my brothers and a sister are all lefties. Only my younger sister is right-handed. I'M PROUD TO BE LEFT-HANDED AND WILL CONTINUE TO BE SO UNTIL THE DAY I DIE! ~
  6. Brendan
    Anyone know the possibility of a family who’s children are all left handed, when parents are right handed?

    I’m ambidextrous and can write with both hands. I’m nearly sure I was left handed until I had a major break on left upper arm. Write with my right, but this next part also is weird.

    When I write with my right my (d) always has a long curl leading to the left. When I write with my left my “d” is perfectly straight, why?
  7. Sabeena Ahmed
    Good to know about the study result. As a biomedical researcher, I was always interested to know the genetic link of Left handedness. I will obviously read the whole report.
    1. H S Hinds
      My maternal Grandmother and Grandfather were both left handed. They had three children two girls and one boy. My mother was the only right handed one of the children and I am the only left handed child of my parents.
  8. L.M.Bannister
    Fascinating and provides more proof that lefties aren’t “deformed” or “wrong”. I hope that more studies will be done in the States (where I live).
    My mother, who is right handed, is one of seven siblings. Two of those siblings are left-handed. I wonder how that came to be seeing as only one in ten of the population in general are left-handed.
    One of my brothers is left-handed. There are four of us. I’m right-handed, my ex-husband is left-handed, and my daughter is left-handed. My left-handed brother married a right-handed woman and all of their three children are right-handed. My right-handed youngest brother has fraternal twin daughters, one of whom is left-handed. Their mother is right-handed.
    I should also note that my brothers have a different father than I and he is right-handed. My father is unknown to me and my mother has never told me whether he’s right or left-handed (I’ve never bothered to ask).
    I also don’t know about the handedness of previous generations.
    I wonder if any studies of the handedness of family groups have been done.
    That would be a very interesting read!
    1. Mrs. A.J. Millington
      Indeed, a handedness study would be interesting. As the oldest of five kids, I am left-handed with 2 brothers and a sister who are the same. Only my younger sister is right-handed. At age 4, my parents forced me to be right-handed. It was quite awkward and left me confused. Using my right hand always resulted in a sloppy right-handed script. Years later while studying my ancestry, I discovered that the left-handed gene (DNA) was on my father's side of the family!
      Early 2017 my right wrist/hand were injured while ice skating SO, EVERYTHING was done with my left hand. After my right hand healed, remaining a southpaw was natural, more comfortable, since that's the way I'm wired. It really is a DNA issue, one deserving further intensive study.
    2. Sabeena Ahmed
      I agree. I am afraid that gathering Vertical gene transfer data will be difficult.

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