A Penn State Behrend professor, Dr. Clare Porac, Professor of Psychology, recently met to discuss the misconceptions about handedness and her work on the subject for a more in-depth look at the subject. Her book “Laterality: Exploring the Enigma of Handedness” is written specifically on the theories and facts about current research around handedness.

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Handedness is split between separate sides of the brain. The book clearly states that “Humans are asymmetrical. The human heart is shifted toward the left side and the brain centres for control of language functions reside in the left hemisphere. The motor control areas of the left hemisphere also regulate the movements of the right hand.” The problem is, however, that there is little evidence to support that a person is “right-brained” or “left-brained.”

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Researchers have found patterns in handedness, and Professor Porac clarified that handedness isn’t a simple dominant-recessive gene relation like attached earlobes, but instead has about 40 different “Genetic Sites” that have to do with handedness. Typically, left-handedness runs in families, and it’s set up in a reverse-sex system. A left-handed father is more likely to have a left-handed daughter than average, with the split going from a 16 percent chance to a 21 percent chance, but has a less-than-average chance of having a left-handed son, where the average 17 percent goes to about 15 percent. A left-handed mother, however, is more likely to have any left handed child, with the average male 17 percent and female 16 percent, spiking to 25 percent and 22 percent respectively.

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A lot of the problems that Porac brought up were related to old, disproven theories that keep showing up. Many news articles claim that left-handed people live shorter lives, and left-handed people are more or less intelligent than the rest of the population, all three of which have been debunked by science from 2010, but keep coming back as clickbait. According to “25 Amazing Facts about Left Handed People” on Leftyfretz, left-handed people are more likely to be homosexual and are better at multitasking. It sounds ridiculous, but Porac sheds light on how these studies are conducted by explaining in a blog post “Research studies often confuse left- and mixed-handedness when comparing handedness groups to each other on a specific variable.”

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A blog post made by Professor Porac actually supports a hypothesis about the reason for such a low density of left-handers, saying,  “I.C. McManus, a prominent expert on theories of handedness, proposes an explanation for this historical dip. He argues that left-handers were ostracized in the 19th century leading to a decrease in their desirability as mating partners. As a consequence of this social stigmatization fewer left-handed children were born to left-handed parents.”

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Porac’s book “Laterality: Exploring the Enigma of Handedness” is available in the Behrend library and the full text is accessible online over Lionsearch. She also has a blog about handedness that can be found at sites.psu.edu/clarep.