The purpose of this study was to clarify the genetic contribution to finger-sucking and nail-biting in childhood using the largest databases available on Japanese twins. The subjects were 1131 pairs of 12-year-old twin children, consisting of 1057 males and 1205 females. All data were gathered by maternal questionnaire, and responses to the questionnaire were checked in the medical interview. The prevalence of finger-sucking between 0 to 2 years was 40% in males and 43% in females. The prevalence of nail-biting up until the age of 12 years was 28% in males and 26% in females. Univariate and bivariate genetic analyses using structural equation modeling was performed. The results showed that the proportion of total phenotypic variance attributable to genetic influences was 66% in males and 50% in females for finger-sucking, and 50% in both males and females for nail-biting. A co-occurrence of finger-sucking and nail-biting was observed in 17.7% of males, which was attributed partly to common genetic or environmental factors. The proportion of total shared variance explained by genetic factors was 67%
I have a nail biting habit and I guess its genetic because my father bites his nails and so does my mother. So does Emily and her aunt. Its seems genetic, I think i would know.
This is a very interesting post. I thought all young children sucked their thumbs, but according to your statistic only 46% do. I never thought as to how these two habits came about in a person. I think both of these are habits that a person can choose to have themselves just by doing it.
I would like to see other arguments as to if this is even genetic. A child probably just develops the habit if they see an adult do it. Children also suck their thumbs because it is similar to having a “binky” in their mouth. There is information to debate about this article. I don’t have a nail biting habit, and neither do my parents. My friends don’t either, and I don’t think these habits have to do with genetics.
I agree with Benjamin Dull. As a child, everyone sucks their thumb. It’s to take place of their pacifier. It’s not genetic.
I think nail biting is a nervous habit, I don’t think it has anything to do with genetics in this case. Some people do it because they can’t keep their fingers still, and others do it because they’re bored. My whole family bites their nails, and I don’t. So I guess it’s NOT genetic, I think I would know.
Wow I didn’t know that biting or sucking thumbs are genetic things!!!
I thought it was just one comman habbit for people. but I guess not.
And the percentage of this habbit is quit huge.
Also I’m agree with Ben that sucking thumbs are not genetic thing but I aree with biting.
Lynn said biting is because of nervous system but nervuos system might also a genetic.
You didn’t post the link to this article. The first paragraph is almost verbatim of this article…
http://www.atypon-link.com/AAP/doi/abs/10.1375/twin.8.4.320
Be sure to summarize the key points of the article…yourself. It is an interesting article.