The majority of the families were of Dutch origin
(>95%). The mean age of the participants at Time 1 was
15.2 years (SD = .60) for the older adolescents, 13.4 years
(SD = .50) for the younger adolescents, 46.2 years (SD =
4.00) for the fathers, and 43.8 years (SD = 3.57) for the
mothers. Of the older adolescents, 47% were girls, compared
to 52% in the younger group. Concerning educational
level, an equal distribution was realized, with about
one third of the adolescents following low education, one
third following intermediate general education, and one
third following the highest level of secondary school.