Handedness

Which hand are you more comfortable writing with? Have you ever thought about that? Or how about why that hand is so much comfortable using than your other hand? It is not completely known why someone is a “lefty” or a “righty.” According to babycenter.com, newborns’ preference for which hand to use is most commonly shown when the baby is anywhere from 6 to 9 months old. However, you won’t be able to fully determine their handedness until they are around 3 years old when they begin to start doing activities such as writing. I believe that handedness is an incompletely dominant gene because even if you are right-handed, you could train yourself to be left-handed, and it is easier for some people to be ambidextrous. It may be easier for those people because they have alleles for “lefty” and “righty”, but only one is normally shown, but if you work at it, both could be used. For example, in the sport of Lacrosse, most of the better players’ stick skills are equal on their left hand and right hand. Therefore, no gene for handedness should be dominant over the other. After doing some research, I have come to the conclusion my theories were incorrect and that handedness has a dominant and recessive allele. According to psychologistworld.com, “Approximately 10-13% of the population is left-handed.” This could mean that the allele for left-handedness is recessive considering that it is so uncommon. Also, according to the same site, “Generally, males are three times more likely to be left-handed than females.” This could show that this gene is sex-linked because men are more likely to show sex-linked traits because all they need is one allele for that trait and there is nothing to go with it because the Y sex chromosome does not carry sex-linked traits. Although humans don’t completely understand how handedness is decided, we do know that genetics is not the only factor. According to babycenter.com, “If both you and your partner are left-handed, your child has a 45 to 50 percent chance of being left-handed as well. “ This confuses me because if my earlier conclusion that being a “lefty” is a recessive gene, then that would mean that if a mother and father were both “lefties”, then neither of them would carry the right handed gene at all, so something else is affecting genes. After reading into this, I have come to another conclusion that babies learn their handedness through what they see during infancy because if both are your parents are “lefties” and you saw them writing things, playing sports, and other activities involving their hands, then as you grow older, you would try to mimic their movements, thus determining your handedness. Therefore, my final conclusion is that handedness is not heredity, it is based on the environment around on you during infancy.