Previous studies have shown that boys more often than girls develop externalizing problem behaviors such as aggression (Keiley, Bates, Dodge, & Petit, 2000), while internalizing problem behaviors such as depressive symptoms are more common in girls, at least in adolescence (Nolen-Hoeksma & Girgus, 1994). Girls are also perceived to be more prosocial, as well, although contradictory findings exist, as reviewed by Eisenberg and Fabes (1998). FinnTwin12 data provide an excellent opportunity to examine gender differences in a variety of socioemotional behaviors in middle childhood and early adolescence using multiple informants. Furthermore, the data permit studying gender differences in genetic and environmental effects on socioemotional behavior.

GENDER DIFFERENCES IN SOCIOEMOTIONAL BEHAVIOR

Multidimensional Peer Nomination Inventory

The multidimensional inventory of children's socioemotional behavior was initially constructed for peer nominations (MPNI; the Multidimensional Peer Nomination Inventory; Pulkkinen, Kaprio, et al., 1999) to represent the two-dimensional model of emotional and behavioral regulation (see Chapter 1). The MPNI consists of 30 items assessing four behavioral types – aggressive, anxious, constructive, and compliant behavioral types – defined by the model. Seven additional items concerning low self-control of behavior were added to Teacher and Parent Rating Forms of the MPNI to increase the coverage of externalizing and internalizing problem behaviors.

A factor analysis of the inventory resulted in three factors for both the MPNI and the Teacher and Parent Rating Forms (Pulkkinen, Kaprio, et al., 1999).