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Disclaimer: This article is for informational purposes only and is not intended for diagnostic use. LifeDNA does not provide diagnostic reports on any traits discussed. Genetics is just one piece of the puzzle; please consult a healthcare professional for comprehensive guidance on any health condition.
Only up to 10% of people are left-handed, so the rest, about 90% are right-handed. And a rare 1% are ambidextrous, meaning they can use both hands equally well. But is being left-handed just a random trait, or is there more to it? Turns out, genetics may play a part. Studies suggest left-handed people may also have unique brain wiring, differences in immune function, and even some varying health risks compared to right-handers.
Understanding these connections may help us learn more about how the brain and body work together, giving left-handed individuals important insights into one’s health.Â
You may want to read: Genetics and Grip: Understanding the Role of DNA in Hand Strength
Handedness refers to the preference most people show for using one hand over the other for tasks like writing, eating, or throwing. The majority of the population is right-handed, meaning they favor their right hand for these tasks. On the other hand, left-handedness, a preference for the left hand, is seen in about 10% of the population.Â
The study of handedness involves understanding the relationship between brain structure and function, particularly how the two hemispheres of the brain control different motor functions. The left hemisphere generally controls the right side of the body, and vice versa. However, handedness isn’t just a matter of left or right, it’s influenced by a mix of genetics, brain function, and environmental factors.
Left-handedness is a trait in which an individual prefers using their left hand for most tasks, including writing, throwing, and other fine motor skills. Unlike the majority of people who are right-handed, left-handed individuals often have the opposite dominant hand. While handedness might appear to be a simple preference, it might be linked to deeper biological processes, particularly in the brain.
The left hemisphere of the brain typically controls the right side of the body, and the right hemisphere controls the left side. In most right-handed individuals, language and fine motor skills are controlled by the left hemisphere, whereas for left-handed people, these functions can be more evenly distributed or even shifted to the right hemisphere. This unique characteristic in left-handed people often leads to different patterns of brain development and organization.
The exact cause of left-handedness is still unclear, but scientists believe it’s shaped by a mix of genetics, brain structure, and environment. Instead of a single “left-handed gene,” research suggests that multiple genes play a role, especially those involved in brain development.
Left-handedness isn’t a medical condition, but it is linked to certain physical and cognitive traits:
Left-handedness can be inherited, but it’s not determined by just one gene. Instead, it is influenced by a combination of several genes and environmental factors. Research shows that left-handedness tends to run in families, meaning that if one parent is left-handed, their child is more likely to be left-handed too, though it’s not guaranteed. Identical twins are more likely to both be left-handed compared to fraternal twins, which also suggests there’s a genetic component at play.Â
However, genetics isn’t the only factor. A study involving over 25,000 twin pairs found that the preferred hand for writing or drawing is a weak genetic trait, with a heritability of just 24%. This indicates that while there’s a genetic influence, other factors also play a significant role in determining handedness.
Several genes have been implicated in the development of handedness. LRRTM1, a gene involved in brain development, has been shown to be associated with left-handedness. Studies have suggested that mutations or variants in this gene can affect how the brain’s hemispheres are organized, potentially leading to a preference for the left hand.
Another gene, DYX1C1 (or DNAAF4), which is associated with dyslexia and other learning disabilities, has also been linked to handedness. This gene plays a role in the migration of neurons in the brain, and disruptions in its function can affect brain asymmetry and the development of lateralization. Similarly, KIAA0319, a gene implicated in dyslexia, has been found to be associated with handedness. Disruptions in these genes may impact brain organization and contribute to the development of left-handedness.
It is important to note that the genetic influence on handedness is likely polygenic, meaning that multiple genes contribute to the trait, and these genes interact with environmental factors in complex ways. Therefore, while certain genetic markers may increase the likelihood of a person being left-handed, no single gene is solely responsible.
While there are some health risks associated with left-handedness, such as an increased likelihood of certain conditions like schizophrenia, heart disease, and breast cancer, many of these findings are still debated.
Left-Handedness and Breast Cancer: Older studies have suggested that left-handed individuals might have a higher risk of breast cancer, with some indicating that it develops earlier in left-handed people. However, more recent research has been inconclusive, and the link between estrogen exposure in the womb and left-handedness has not been proven.
Left-Handedness and Schizophrenia: A number of studies have found that left-handed individuals may be more likely to develop schizophrenia. This connection may be due to differences in brain organization, with left-handed people exhibiting less lateralization (specialization) between the brain’s hemispheres, a feature often associated with schizophrenia. Further research has supported this, showing a higher incidence of mixed-handedness in those with schizophrenia.
Left-Handedness and Mental Health: Research has shown that left-handed people may experience certain mental health symptoms, including mood swings, anxiety, and irritability. Mixed-handedness has been more strongly linked to conditions like PTSD, though the evidence for depression in left-handed individuals is minimal.
Left-Handedness and Alcohol Consumption: Though some earlier research proposed that left-handed individuals drink more alcohol, a 2022 study found no significant correlation. Previous findings may have been influenced by societal biases and stigma.
Left-Handedness and Heart Disease:Recent studies have raised concerns that left-handed individuals may have a higher risk of cardiovascular disease. However, no clear cause has been identified, and more research is needed to determine why this might be the case.
The LifeDNAReports provide personalized insights into how your genetic makeup influences various aspects of your well-being, including nutrition, fitness, sleep, and personality and cognition. By understanding these genetic influences, you can make more informed choices about your lifestyle and wellness.Â
Whether you’re left-handed or just curious about how your genes shape your handedness, the LifeDNA Wellness Report provides important information on many interesting genetic traits. Our Report looks at your genetic make-up to help you understand your strengths, potential risks, and how you can improve your wellness. This way, you can make better choices based on your unique genetic makeup. Get yours here.
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