Behavioural Genetics of Early Childhood: Fears, Restlessness, Motion Sickness and Enuresis

Abstract

AbstractSeventy-nine pairs of same-sex twins were examined at the age of three years at a municipal clinic and their mothers were interviewed to assess the twins' current and past behaviours. The zygosity was determined after the interview by fingerprints and/or bloodtyping in the majority of cases. The following significant differences in concordance between monozygotic and dizygotic twins were found: 1) fear of strangers during observation at the clinic; 2) marked fear of strangers in the first year of life; 3) whether or not the child was startled by sudden noises during infancy; 4) whether or not the child was able to sleep alone at three years without a parent sitting nearby; 5) susceptibility to motion sickness; 6) nocturnal enuresis; 7) short attention span or restlessness during the test.