Coffee drinking habits partly shaped by genetics, Korean twin study finds

Does the habit of drinking coffee run in the family? A study analyzing Korean twins found that genetic factors account for some of the individual variation in coffee-drinking behavior, but personal environmental factors play a larger role.

According to the Korea Food Communication Forum, a joint research team — including Lee Jeong-eun, a professor in the Department of Food and Nutrition at Seoul National University, researcher Cho Min-su, and Yoon Ji-young, a professor in the Department of Food and Nutrition at Chung-Ang University — examined how much genetic and environmental factors influence coffee, tea and caffeine consumption among Korean twins. The study was recently published in the international journal Behavior Genetics.

The research team analyzed 1,106 twins aged 30 and older. About 88 percent of the participants currently drank coffee, and about 78 percent drank tea. Average daily caffeine intake was approximately 64.9 milligrams.

The study found that genetic factors explained 29 percent of the individual variation in whether a person drinks coffee — meaning roughly 29 percent of the observed differences in coffee-drinking behavior among the study group could be attributed to genetic differences. The remaining 71 percent was explained by unique environmental factors, which include individual-specific environmental influences and measurement error. For tea drinking, the genetic contribution was even lower: heritability stood at 11 percent, with unique environmental factors accounting for 89 percent.

When the research team divided participants into high- and low-intake groups based on the median daily caffeine intake of 55.55 milligrams, heritability came in at 27 percent, with unique environmental factors explaining 73 percent. When caffeine intake was analyzed as a continuous variable, the estimated heritability was 17 percent.

The findings suggest that while genetics play some role in coffee and caffeine consumption, genetic factors alone cannot fully explain coffee-drinking behavior. Particularly for coffee drinking, individual environmental factors carried more weight than genetic ones.

Physiological responses to caffeine and the rate at which it is metabolized can vary from person to person. Caffeine works by blocking adenosine receptors in the brain, reducing drowsiness and increasing alertness. Genetic differences involved in caffeine metabolism and response may also be linked to how individuals react to caffeine.