Temperament and psychiatric disorder: the genetic contribution to behaviour in childhood.

The studies stemming from the New York longitudinal study of temperament in childhood are summarised and conceptual difficulties and problems arising from them are described. An alternative model of temperament provided by Buss and Plomin is also considered. Finally, a new typology of temperament is proposed. It is based on the suggestion that ordinary, non-pathological behaviours, in extreme form, can be viewed as manifestations of emotional disorder, hyperactivity and antisocial disorder. Empirical evidence derived both from twin studies and from epidemiological investigations is put forward to support this view.