Data were collected as part of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study of the outcome of early risk factors from infancy into adulthood [24]. The initial sample comprised 384 children of predominantly (>99.0%) European descent, born between 1986–88. Infants were recruited from two obstetric and six children’s hospitals of the Rhine-Neckar Region of Germany and were included consecutively into the sample according to a two-factorial design intended to enrich and control the status of the sample regarding obstetric and psychosocial risks (full details of the sampling procedure have been reported previously) [25]. Only firstborn children with singleton births and German-speaking parents were enrolled in the study. As well, children with severe physical handicaps, obvious genetic defects, or metabolic diseases were excluded. Assessments were conducted at regular intervals throughout development, most recently at the age of 19. Of the initial sample of 384 participants, 18 (4.7%) were excluded because of severe handicaps (IQ<70 or neurological disorder), 39 (10.2%) were dropouts, 35 (9.1%) refused to participate in blood sampling and 24 (6.3%) had incomplete data. Accordingly,
