Prenatal development depends on carefully orchestrated developmental stages. At any stage, sex hormone irregularities, genetic abnormalities, or exposure of the fetus to in­appropriate maternal hormones can result in atypical sexual differentiation. The result can be a child born with ambiguous genitals or with the external genitals of one sex and the genetic makeup of the […]

External genitals follow a pattern similar to internal organs, except that male and fe­male genitalia all develop from the same tissue. Male and female organs that began from the same prenatal tissue are called homologous (HOE-mol-lig-gus). Until the 8th week, the undifferentiated tissue from which the genitalia will develop exists as a mound of skin, […]

A human embryo normally undergoes about 9 months of gestation. At about 4 to 6 weeks, the first tissues that will become the embryo’s gonads develop. Sexual differenti­ation begins a week or two later and is initiated by the sex chromosomes, which control at least four important aspects of sexual development: (1) the internal sexual […]

Human beings have a biological urge to reproduce and so are in some sense “designed” to be sexual beings; any species that does not have good reproductive equipment and a strong desire to use it will not last very long. Simpler organisms, such as amoebas, sim­ply split in two, creating a pair genetically identical to […]

Prenatal Development: X and Y Make the Difference Sexual Differentiation in the Womb Atypical Sexual Differentiation: Not Always Just X and Y Gender Roles and Gender Traits Girls Act Like Girls, Boys Act Like Boys Are Gender Roles Innate? Studying Gender Gender Role Theory Evolutionary Theory: Adapting to Our Environment Social Learning Theory: Learning From […]

Many view America as a country “obsessed with sex.” As we discussed in Chapter 1, sex is used to sell everything from blue jeans to cologne and is oozing from television sitcoms, ad­vertising, music videos, and pop lyrics. However, even with this openness and sex all around us, there is a painful lack of solid […]

Internet-Based Sexuality Research n 2000 it was estimated that two-thirds of Americans used the Internet, and this number con­tinues to grow today (A. C. Nielsen, 2000). It is esti­mated that the average Internet user in the United States spends 3 hours per day online (Markoff, 2004). The popular­ity of the Internet has led to an […]

The Pfizer Global Study of Sexual Attitudes and Behaviors In 2002, Pfizer Pharmaceuticals did the most comprehensive global study of sexual­ity to date (see the accompanying Human Sexuality in a Diverse World). The Pfizer Global Study of Sexual Attitudes and Behaviors surveyed over 26,000 men and women in 28 countries. This study was the first […]

Many studies examine sexuality in cultures outside the United States. Some have been general studies that examine knowledge levels and attitudes in different populations; others have evaluated specific areas such as pregnancy, rape, homosexuality, or sex edu­cation. Many times these studies are done by researchers in other countries, but some have also been done by […]

How reliable is sex research? Some studies have found that couples who are sexually sat­isfied tend to overestimate their frequency of sexual behavior, whereas those who are un­satisfied underreport it (James, 1971). In 1967, a study was done to evaluate the relia­bility of the reporting of sexual activity. Men were required to keep daily logs […]