The Helsinki Birth Cohort Study (HBCS) is a birth cohort sample of individuals born at Helsinki University Central Hospital in 1934–44.23, 24, 25 Temperament data used in these analyses were collected in 2004; 1671 persons had valid phenotype data, and of these 1425 were genotyped and passed QC (60% female). The mean age of participants was 63.4 (±2.9) years.
