In 2011-2013, data were collected from adults who were the parents (833 mothers and 577 fathers) of the children participating in ECPBHS. To create new knowledge, both children’s and parents’ data will be merged. The study seeks to identify genetic and environmental influences on the development of different psychological, health and physical traits by examining children and parents together. As health, personality, impulsivity, behaviour and other traits are influenced by both environmental and genetic factors, it is important to clarify whether family relations depend on target genotypes of family members and on child-parent genotype interactions. The study of ECPBHS parents was carried on by scientists from University of Tartu and National Institute for Health Development in Estonia.