Gender-typical behavior in humans is influenced by biological, psychological, social, and cultural factors. These factors are associated with differences between boys and girls in certain behaviors (e.g., aggressive and pro-social behaviors), as well as gender-typical preferences in toys and activities, playing habits, and friends (Bosinski, 2000, Hines, 2004 and Ruble et al., 2006). Given the complexity of influences on psychosexual development, it is difficult to estimate the effect size of each factor (e.g., biological, social, cultural, individual) on gender-related behavior and preferences (Houk et al., 2004 and Iervolino et al., 2005).
In humans, gonadal hormones are thought to play an important role in the development of gender-related behaviors. Androgen effects on the developing brain and consequent behaviors have been documented in a range of mammals (Arnold, 2002, Dohler et al., 1984, Hines and Collaer, 1993, Lephart et al., 2001 and Sato et al., 2004). High concentrations of prenatal androgens contribute to male-typical behavior development, whereas female-typical behavior develops in the absence of high levels of androgens (Breedlove et al., 1999, Collaer and Hines, 1995, Hines, 2002, Hines et al., 2002 and Hrabovszky and Hutson, 2002).
Disorders of sex development (DSD) provide a unique opportunity to study the effects of prenatal androgen exposure and gender-specific socialization on the development of gender-related behavior. Several studies of girls with congenital adrenal hyperplasia (CAH), an enzymatic defect in adrenal steroid synthesis resulting in high levels of prenatal androgens that lead to genital masculinization in affected female children, show that they differ markedly in gender-related behavior from unaffected girls (Berenbaum, 1999 and Cohen-Bendahan et al., 2005). Girls with CAH, as a group, show an increased preference for typical “boys' toys” (Berenbaum and Hines, 1992, Berenbaum and Snyder, 1995, Dittmann et al., 1990 and Slijper, 1984) and male playmates (Berenbaum and Snyder, 1995), show more aggressive behavior (Berenbaum and Resnick, 1997), and are less interested in maternal rehearsal play, feminine make-up and accessories (Dittmann et al., 1990, Ehrhardt and Meyer-Bahlburg, 1981 and Leveroni and Berenbaum, 1998).
Children with an XY karyotype may also be affected by DSD leading to physical hypoandrogenization. In androgen insensitivity syndrome (AIS), the testes produce normal to high levels of androgens, however, functioning of the androgen receptor is completely (cAIS) or partially (pAIS) impaired, affecting physiological masculinization of the urogenital tract and the external genitalia. Defects in androgen biosynthesis [e.g., 17β-hydroxysteroid-dehydrogenase-3 deficiency (17βHSD3)], 5α-reductase-2 deficiency (5αRD), and gonadal dysgenesis cause insufficient androgen production to induce normal male-typical anatomical development (Bahceci et al., 2005, Hiort et al., 2002 and Hiort and Holterhus, 2003). These conditions lead to a lack of androgen action, and the phenotype of affected individuals may range from predominantly male to typically female (Ahmed et al., 2000, Boehmer et al., 1999, Galli-Tsinopoulou et al., 2003, Hiort et al., 1996, Holterhus et al., 2000, Melo et al., 2003, Simpson and Rajkovic, 1999, Sinnecker et al., 1996, Sinnecker et al., 1997 and Thiele et al., 2005).
Compared with the number of studies of girls with excessive androgen exposure in prenatal life, studies assessing the effects of androgen insensitivity or lack of androgens on gender-typical behavior in children with 46,XY karyotype are scarce (al-Attia, 1996, Cohen-Kettenis, 2005, Cohen-Kettenis and Pfäfflin, 2003, Hines et al., 1998, Hines et al., 2003, Mendonca et al., 2000, Wilson, 2001 and Zucker, 1999).
The aim of this study was to evaluate gender-related activities, play preferences, and interests of prepubertal children with 46,XY karyotype and DSD with varying prenatal androgen exposure and to compare them with same-age children without such conditions. Following a dose–response hypothesis we assume that masculinization of gender-related behavior is a function of prenatal androgen effects. If prenatal androgen exposure contributes to the development of gender role behavior, then individuals with an XY karyotype with complete hypoandrogenization (i.e., complete androgen insensitivity syndrome; cAIS) would exhibit the least masculine behavior followed by those with partial hypoandrogenization. In addition to the biological influences of androgens on gender role development, sex of rearing may support gender-typical behavior; i.e., more female-typical and/or less male-typical behavior in those with partial androgen exposure reared as girls compared to those reared as boys.
