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You’ve blamed sleeping on your head funny, the heat, the humidity and your new shampoo — but bad hair days all come down to our genes, according to a new study.
The flow and shape your hair takes is dictated by “wisps,” a spot that grows in a circular pattern, usually at the crown of your head. And scientists have now discovered four genetic variants that change the direction and appearance of the whorls.
The point of the whorl is determined by the direction of the hair follicles, and the whorls are easy to identify from person to person.
Patterns are usually defined by the whorl number, single crown or double crown, as well as whorl direction, clockwise, counterclockwise or even diffuse.
Some people with double crowns worry about going bald, and diffuse swirls can be hard to control, but the new study had more serious medical concerns in mind than the DNA behind a perfectly coiffed haircut.
Atypical hairline patterns have been observed in patients with abnormal neurological development. Left (a), two common whorl patterns. Right (b), statistical plots of the large genetic study that identified four genetic variants associated with hair whorl variations
Genetic variants 7p21.3, 5q33.2, 7q33 and 14q32.13 have been found to influence the direction of rotation by changing the shape of hair follicles. Before this new study, the prevailing opinion was that hair whorls were controlled by a single gene, among classic dominant/recessive traits
Atypical whorl patterns have been observed in patients with abnormal neurological development – leading doctors and geneticists to investigate whether there might be an actual hereditary link between the two.
Genetic variants 7p21.3, 5q33.2, 7q33 and 14q32.13 were found to influence the direction of the hair follicle by shifting the shape of the hair follicle.
But according to the new research from the Chinese Academy of Sciences, developmental changes early in life, including the closure of the cranial nerve tube and the growth of the nervous system during fetal formation, will also play a key role.
“We know very little about why we look the way we do,” said the study’s lead researcher, Dr. Sijia Wang of the Chinese Academy of Sciences’ Shanghai Institute of Nutrition and Health.
“Our group has been looking for the genes underlying several interesting physical appearance traits, including fingerprint patterns, eyebrow thickness, earlobe shape and hair curl,” said Dr. Cheek.
“Wreath of hair is one of the traits we were curious about. The prevailing opinion was that the direction of the hair whorl is controlled by a single gene, which shows a Mendelian inheritance.’
Dr. Wang and the academy’s team of researchers studied the whorls and full genomes of 2,149 Chinese, then another 1,950 Chinese nationals to replicate their own results for their study, published today in the Journal of Investigative Dermatology.
The results showed a strong correlation between the four genetic variants and certain whorl behaviour.
But no less importantly, the study found suggestive but preliminary evidence that rejected the idea that unusual hair swirls and brain developmental disorders may be linked.
“Our results show that the direction of hair whorl is influenced by the cumulative effects of multiple genes, suggesting a polygenic inheritance,” said Dr. Cheek.
“Previous work hypothesized associations between hair swirl patterns and abnormal neurological development,” he noted.
“No significant genetic associations were observed between the direction of the hairline and behavioral, cognitive, or neurological phenotypes,” said the large genetic study by he and his co-researchers.
“While we still know very little about why we look the way we do,” said Dr. Wang, “we are confident that curiosity will eventually lead us to the answers.”