Sexuality and Gender 397Others note that it involves real biological changes. One study showed these men pro-
duce female hormones normally associated with the production of breast milk (Storey
et al., 2000). It may be a way for some men to work through their feelings about impend-
ing fatherhood. Or it may be related to how emotionally sensitive they are, or prone to
personal distress (Kazmierczak et al., 2013). Whatever the cause or causes, couvade syn-
drome remains a fascinating condition that seems to defy ordinary gender roles.
BIOLOGICAL INFLUENCES Most researchers today would agree that biology has an
important role in gender identity, at least in certain aspects of gender identity and behavior
(Diamond & Sigmundson, 1997; Money, 1994; Reiner, 1999, 2000). In one study, 25 geneti-
cally male children who were born with ambiguous genitalia were surgically altered and
raised as girls. Now, as older children and teenagers, they prefer male play activities such
as sports. Fourteen of these children have openly declared themselves to be boys (Reiner,
2000; Reiner & Gearhart, 2004).
What are the biological influences on gender? Aside from the obvious external sex-
ual characteristics of the genitals, there are also hormonal differences between men and
women. Some researchers believe that exposure to these hormones during fetal develop-
ment not only causes the formation of the sexual organs but also predisposes the infant
to behavior that is typically associated with one gender or the other.
Gender appearance rigidity is a developmental stage many preschool age children seem
to experience. Girls will insist upon wearing dresses, the frillier the better, even though only
a few weeks ago they would happily wear pants. Boys begin to refuse to wear anything that
might be considered “girlish.” Researchers studying the prevalence of this behavior found
that two thirds of the girls and nearly half of the boys went through a stage of rigid adherence
to gender-typed clothing and toys, regardless of their parents’ preferences for the same items
(Halim et al., 2014). This observation held true in a diverse selection of children in the United
States from both ethnically and economically diverse backgrounds. But is this rigidity stage
due to biology or to environmental influences? Even if parents try not to influence their chil-
dren’s gender behavior, exposure to gender role stereotypes from other sources—the media,
preschool, other children, teachers, and books, for example—is nearly impossible to control.
There have been several studies of infant girls who were exposed to androgens
before birth (for example, some drugs to prevent miscarriages are male hormones).
In these studies, the girls were found to be tomboys during early childhood—prefer-
ring to play with typically “boy” toys, wrestling and playing rough, and playing with
boys rather than with other girls (Berenbaum & Snyder, 1995; Money & Mathews, 1982;
Money & Norman, 1987). However, when these girls grew up, they became more typi-
cally “female” in their desire for marriage and motherhood, which many of these same
researchers took as evidence that upbringing won out over the hormonal influences.
Was their early tomboy nature due to the influence of the male
hormones?This is difficult to prove, as the parents of these girls were told about their infants’
exposure to male hormones during the pregnancy and may have formed assumptions
about the effects of such masculinizing hormones on their children. It is entirely possible
that these girls were simply allowed, or even encouraged, to be more “masculine” as small
children because the parents were expecting them to be masculine. As these same girls
grew older, they were exposed to the gender-role expectations of teachers, friends, and the
media, which may have influenced them to become more like the feminine gender stereo-
type in contrast to their earlier “masculine” style of behavior. Some studies have attempted
to investigate factors by researching the behavior of nonhuman animals. For instance, as
the video Gender Socialization explains, male and female vervet monkeys appear to prefer
typically “boy” and “girl” toys, such as trucks and dolls respectively, indicating a possible
biological influence.