King's College London

G1219 is a longitudinal study that aims to examine the interplay between genes and the environment on the development of anxiety and depression over time. We have also regularly assessed other aspects of development including aggression and sleep quality, and environmental experiences including life events and peer group difficulties.

The study started in 2000. The twins (N = 1381 pairs) were recruited through the Office of National Statistics, and the siblings (N = 1747, including 445 pairs) were offspring of participants who took part in a large study of depression. All participants were aged between 12 and 19 years (Mean = 14) at wave 1 of data collection. Since this time, 4 further waves of data collection have occurred.

All data collected in this study has been through questionnaires, with most data self-reported by the participants themselves with parent report data obtained at waves 1 and 3. DNA was collected from a proportion of the sample over time (N = 1237).

The main focus of this study has been the role of genetic and environmental influences on the development of emotional and behavioural problems across adolescence.