By Kim Rahn
Staff Reporter
A state-sponsored study on twins showed that height and other features are largely genetically determined, while environmental factors tend to have a greater influence on behavioral characteristics in general.
The results come from a study on these twins conducted by the Korea Center for Disease Control and Prevention and a team of researchers since 2005.
According to the four-year project tracking 550 pairs of twins aged over 35 and 1,200 of their family members, height was hereditary 65 percent of the time, meaning genetic factors were 65 percent attributable to phenotypic variance.
``The hereditariness of twins differs slightly from country to country, as each has its own environmental factors, meaning genetic factors are 65 percent responsible for deciding a Korean individual's height,'' said Sung Joohon, a professor at Seoul National University's Graduate School of Public Health.
The hereditariness of high-density lipoprotein (HDL) cholesterol was 60 percent and that of low-density lipoprotein cholesterol, 55 percent. The proportion of genetic factors in weight was 50 percent and that in blood pressure, about 45 percent.
Habits were also partly decided by genes ― genetic factors were 40 percent responsible for dependence on nicotine.
However, it was found that many twins showed very different aspects in eating habits and obesity levels when they became adults ― a result of environmental factors. Smoking habits, obesity levels and blood pressure are developed by a combination of genetic and environmental factors, Sung said.
``The study can be applied to not only twins and their families but everyone. In regard to nicotine addiction, for example, it means that people who are dependent on nicotine can quit smoking through willpower and making environmental changes, as environmental factors are 60 percent responsible for the addiction,'' Sung said.
The researchers will keep studying the twins to find more hereditariness in diseases. The study's results were recently published in an international science journal, Twin Research and Human Genetics.