Are you born left-handed?

No, I am not left-handed.  Actually, no one in my family is a “lefty” (except one of my cousins).  So I decided to do this blog for her.  When I think about left-handedness, I believe, personally, that it is in one’s genes.  That was my hypothesis going into this; one is born left-handed and it gets passed down.

During my research, I fell upon an article from the Scientific American, where Clare Porac, who is actually a professor of psychology here at Penn State (WE ARE!) pointed out that left-handedness begins either in genes or by biological causes.  One theory she found was that natural selection created lots of people with language and speech control on the LEFT side of their brain.  The LEFT side of the brain is known to control the RIGHT hand and written language.  They say there are two alleles, the D gene and the C gene.  The D gene is the right-handed gene and the C gene is the left-handed gene.  If someone has the C gene, they have a fifty-percent chance of being left-handed, which is minimal in this case.

In a resent article from PLOS Genetics, they did a genome-wide association study meta-analysis and discovered that certain genes are related to left/right body asymmetry.  They used mice to test this hypothesis, very similar to humans.  So since this seems to be a genetic thing, why is left-handedness still occurring?  That is because this left-handedness occurs as a result of a lot more genes than just dominant and recessive ones like the old days.  Wonderopolis.org says, “since scientists have noticed that left-handedness tends to run in families, it’s assumed that left-handedness has a genetic component to it. In other words, left-handers are born that way.”

Another study took a little different of a toll on this idea.  This study, done in 1972 by British psychologist Marian Annett, was also known as the Right Shift Theory.   She concluded that left-handers do not inherit the gene for left-handedness, instead they get the absence of neurological bias toward the dominant left hemisphere.  She also said random events during one’s childhood, such as a school telling a kid to use their right hand to write and not left, may actually lead to a little bit of influence on the actual handedness.  This means that genetics make more of a difference for right handers because they have more dominant handedness genes in general.  

Maybe in the future, some more testing can be done.  Maybe…is it possible for someone to change their handedness on their own?  We could get one group of right-handed people and try to train them to write with their left-hand and see if it works.  You never know unless you try, right?  So in conclusion, they are many reasons scientists believe one is left-handed.  From my research, I have learned that the majority of these people believe it comes from genes.

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Works Cited:

  1. http://www.scientificamerican.com/article/what-causes-some-people-t/
  2. http://www.smithsonianmag.com/science-nature/why-are-some-people-left-handed-6556937/?no-ist
  3. http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1003751
  4. http://wonderopolis.org/wonder/why-are-some-people-left-handed
  5. http://www.rightleftrightwrong.com/theories_genetic.html

8 thoughts on “Are you born left-handed?

  1. Julia Hall

    This article is really interesting because I am left handed. My dad is left handed too so I think it’s right to assume that being left handed is a genetic trait. A few other people on his side of the family are left handed too. Though I write with my left hand, I do alot of thing with my right hand and right foot. I play sports as if I was a righty. I can play sports as a lefty but do much better as righty which I think is interesting. It is honestly hard being a left handed person when it comes to school work because the binder rings are always in the way, a lot of time classrooms only have righty convertible desks and I always have pen or pencil on the side of my left hand because I always smudge it as I write.

  2. Erik Samuel Ridley

    As a proud left-hander, I found this a fascinating topic. Your thought about training the other hand was very interesting as I once had to attempt just that. I broke a finger on my left hand and for a couple weeks had to try writing as a righty. It was definitely tough to overcome, but I got better as the days rolled by, making me agree with one of the comments above that psychology may yet play a role in this debate. I also believe that you can change hands in your developmental years, as I play golf right handed even though I am a lefty.

  3. Caroline Gail Stacks

    I found this article to be interesting due to many personal stories that have always sparked my curiosity. First of all, there has been one girl in every generation of my mom’s side that was left-handed. I am left-handed, my mom was, my grandmother is left-handed, my great-grandmother, and my great-great-grandmother! I have always wondered if this was pure chance, or if it was genetics. Also, my brother is right handed, but when he was little he seemed to be ambidextrous. He would pick up his writing utensil with his left hand sometimes, and his right hand others. When he would go to soccer or baseball practice, he would kick with his left foot or bat left handed some days, but then would do the opposite at other practices. Eventually, though, he began to do everything with his right hand. Since he is adopted, we don’t have any idea if his parents were right or left-handed. So in my situation, it seems likely that being left-handed does have to do with genetics, but in my brother’s case, it seems a bit more confusing! But I guess for my brother it’s a good thing he chose to be right-handed, since left-handers apparently die sooner than people who write with their right hands!

  4. Aubree Sylvia Rader

    I actually knew someone personally who was raised in the 1940’s when it was believed that left-handed kids were not bright. His parents would keep a sock on his left hand while growing up to train him to make his right hand his dominate hand. It would be interesting to look into whether that has any affects on the brain. If one’s brain is programmed to use the left hand, what would changing that do? Also, why are some people ambidextrous? My mom is left-handed yet she does everything but write using her right hand. I found that only 1% of the population is ambidextrous which you can read about here http://www.apa.org/monitor/2009/01/brain.aspx. You might want to consider exploring ambidexterity, which could be very interesting.

  5. Holly Rubin

    Although I am not left handed. there are many people in my family that are. I always assumed that they were left handed due to genetics and that left handness is a recessive trait in my family. I never even thought that it was possible that they were left handed because of environmental components or creation of habits such as the ones discussed in your blog. When I was younger I used to always wonder why everyone isn’t right handed, especially since it’s possible to train people to be it. But, people are dominant in the hand that they were born to be dominant in.

  6. Jada Baity

    When my brother was younger, he was ambidextrous. This means that sometimes he would use his right hand to write and other times he would use his left hand. It confused my parents because, if left-handedness is genetic, they could not understand why my brother was using his left hand because my entire immediate family is right handed. In fact, the only reason my brother is left handed today is because my parents forced him to pick only one hand to write with when he was young. So I side with the argument that says that left-handedness is a psychological thing rather than a genetic thing. A child only knows what its taught. So when a child learns how to write with their left hand, whether in school or at home, they will write with their left hand. It is as simple as that.

  7. Alexandra Herr

    This topic is one that seems to be very overlooked, so I am glad you took the time to write one of your blogs on it. In agreement with psychologist Marian Annett, one of my good high school friends believed that she was born left handed but developed stronger with her right hand because that’s what everyone else was using in school and in her household. This is an example of an outside pressure altering her hand strength. Personally, I hypothesize that either hand can be trained to be the more dominant one, but it usually happens to be the right one because that is was people are taught is superior. It would have been interesting if you researched ambidexterity to see some possible studies behind the causes of that.

  8. Angelique L Santiago

    I found this article very interesting. I think it would also be cool to take this blog a bit farther and discuss people who are lefty’s for some aspects of their lives, but not others. For example, my brother plays basketball, and when he plays basketball he handles the ball with his left hand. Also, when he plays soccer he kicks with his left foot, as do I, because I play soccer too. However, both me and my brother write with out right hands. Strange, right? From your blog I now know that left-handedness is most likely genetic. At the same time, I still wonder why the left and right sides vary dominance depending on what the situation is. You can always read more about what makes a person left-handed in the following link if you want 🙂
    http://kidshealth.org/kid/talk/qa/lefties.html

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