Genetic factors that are associated with fears appear to change as children and adolescents age, with some familial factors declining in importance over time while other genetic risk factors arise in adolescence and adulthood, according to a report in the April issue of Archives of General Psychiatry.
The nature of common fears changes during childhood and adolescent development, according to background information in the article. Two hypotheses have been proposed regarding genetic risk factors for these fears. “The ‘developmentally stable' hypothesis predicts that a single set of genetic risk factors impacts the level of fears at age 8 years and these same genes constitute the only genetic influences on fear-proneness throughout development,” the authors write. “By contrast, the ‘developmentally dynamic' hypothesis predicts that genetic effects on fear-proneness will vary over time.”
Kenneth S. Kendler, M.D., of the Virginia Commonwealth University School of Medicine, Richmond, and colleagues studied 2,490 twins born in Sweden between 1985 and 1986. The twins were assessed for their level of fear four times: at age 8 to 9 by a questionnaire mailed to parents, at ages 13 to 14 and 16 to 17 with questionnaires mailed to twins and parents and at age 19 to 20 with questionnaires only to the twins.