Instructor’s Manual
to accompany
Discovering Human Sexuality, Third Edition
LeVay • Baldwin • Baldwin
Chapter 4: Sex, Gender, and Transgender
Chapter Overview
Males and females differ genetically, anatomically, physiologically, and behaviorally.
How embryos develop as male or female and the relative contributions of the X and Y
chromosome are both explained at the beginning of the chapter. The discussion includes a
detailed summary of the development of the gonads, the ducts, and the external genitals
in male and female embryos. Sexual differentiation of the male and female brain is
addressed along with disorders of sex development—or conditions in which
chromosomal, gonadal, or genital sex are discordant or ambiguous.
Gender, or the collection of mental traits that differ between women and men is covered
in detail from a biological, social/environmental, and sexual perspective. The chapter
ends with a thorough discussion of issues directly related to a transgender identity, such
as transexuality, transitioning, hormonal interventions, and sex-reassignment surgery.
The reasons why some transgender individuals do not seek sex reassignment are also
considered.
Chapter Outline
Genes and Hormones Guide Sex Development
Female and male reproductive tracts develop from different precursors
Female and male external genitalia develop from the same precursors
The gonads descend during development
Puberty is sexual maturation
The brain also differentiates sexually
Sex Development May Go Awry
Chromosomal anomalies affect growth and fertility
The gonads or genitals may be sexually ambiguous
Box 4.1 My Life with Androgen Insensitivity Syndrome
Gender Is a Central Aspect of Personhood
Gender identity might not match anatomical sex
Women and men differ in a variety of cognitive and personality traits
There Are Many Sex Differences in Sexuality
Many gender differences arise early in life
Biological Factors Influence Gender
Evolutionary forces act differently on females and males
Box 4.2 Gendered Play in Primates
Experiments demonstrate a role for sex hormones
Life Experiences Influence Gender
Gender is molded by socialization
Cognitive developmental models emphasize thought processes
Gender Development Is Interactive
Box 4.3 The Boy Who Was Raised as a Girl
Transgender People Cross Society’s Deepest Divide
Box 4.4 Trans Men and Women in Cross-Cultural Perspective
Transexual individuals are of more than one kind
Changing sex is a multistage process
Some transgender people do not want surgery
Box 4.5 How Should We Treat Gender-Dysphoric Children?
Trans people struggle for awareness and acceptance
Learning Objectives
1. Provide a complete survey of the process of sexual differentiation of the internal and
external reproductive structures of males and females.
Textbook Reference: Genes and Hormones Guide Sex Development, pp. 88–92
2. Summarize, with examples, the chromosomal abnormalities that affect growth and
fertility and outline what can cause the gonads and genitals to be sexually ambiguous.
Textbook Reference: Sex Development May Go Awry, pp. 93–96
3. Summarize the research findings related to sex differences in cognitive function,
personality differences, and sexual attitudes.
Textbook Reference: Gender Is a Central Aspect of Personhood, pp. 97–99
4. Outline the sex differences seen in human sexual behavior.
Textbook Reference: There are Many Sex Differences in Sexuality, pp. 99–101
5. Provide an account of the gender differences seen in children, from early infancy until
puberty.
Textbook Reference: There are Many Sex Differences in Sexuality, pp. 101–102
6. Discuss the explanation provided by evolutionary psychology to account for the sex
differences seen in cognition, jealousy, and sexuality.
Textbook Reference: Biological Factors Influence Gender, pp. 102–103
7. Provide a summary of the evidence that many gendered traits may be caused by
differential exposure to prenatal hormones.
Textbook Reference: Biological Factors Influence Gender, pp. 103–104
8. Explain the socialization account of gender development, including influences from
observational learning, rewards and punishments, imitation, language, and gender rules
inculcated across childhood.
Textbook Reference: Life Experiences Influence Gender, pp. 105–108
9. Describe the various types and classifications of transgender individuals. Provide a
discussion of the types and forms of transgenders seen across different cultures.
Textbook Reference: Transgender People Cross Society’s Deepest Divide, pp. 110–113
10. Describe the various stages of sex reassignment surgery. Discuss the factors that
influence a person who is considering this type of surgery and the reasons that many
transexuals choose not to have surgery.
Textbook Reference: Transgender People Cross Society’s Deepest Divide, pp. 113–118
Chapter Summary

Sex is usually determined by the sex chromosomes: The XX pattern causes female
development, and the XY pattern causes male development. The key player in male
development is the gene SRY, on the Y chromosome, which induces the embryo’s
genital ridges to become testes. In the absence of SRY, other genes induce the genital
ridges to become ovaries.

The male and female internal reproductive tracts develop from different precursors—
the Wolffian and Müllerian ducts. In XY embryos, the testes secrete anti-Müllerian
hormone (AMH), which causes the Müllerian ducts to regress, and androgens, which
cause the Wolffian ducts to develop further and produce the male internal anatomy. In
XY embryos lacking functional androgen receptors (a condition called androgen
insensitivity syndrome), neither the male nor the female reproductive tract develops.
In XX embryos (normal females), the lack of AMH allows the Müllerian ducts to
develop further, and the lack of androgens allows the Wolffian ducts to regress,
producing the female internal anatomy.

The external genitalia of the two sexes develop from common precursors. The
urethral folds give rise to the inner labia in females and to the shaft of the penis in
males. The genital swellings give rise to the outer labia in females and the scrotum in
males. The genital tubercle forms the external portion of the clitoris in females and
the glans of the penis in males. Male-typical development of the external genitalia
requires the presence of testosterone and its conversion to 5-dihydrotestosterone
(DHT). In female fetuses that are exposed to high levels of androgens (as in
congenital adrenal hyperplasia), the external genitalia are partially masculinized.

Male and female brains differ in structure, chemistry, and function. Some sexual
differentiation of the brain occurs prenatally—high levels of androgens drive maletypical brain development, and low levels permit female-typical development. At
puberty and thereafter, estrogens become important in establishing and maintaining
female-typical body structure and function and also influence the brain.

Disorders of sex development include chromosomal anomalies such as Klinefelter
syndrome (XXY or XXXY) and Turner syndrome (XO), as well as genetic conditions
that affect sex hormone production (e.g., congenital adrenal hyperplasia) or the
body’s sensitivity to sex hormones (e.g., androgen insensitivity syndrome). The
proper treatment of children with ambiguous genitalia is a subject of controversy.

Gender is the entire collection of mental traits that differ between women and men.
Gender identity is a person’s core sense of being a woman or a man. Gender role is
the social expression of gender identity.

On average, women outperform men in fine movements, verbal fluency, and some
aspects of memory. Men outperform women in some cognitive traits, such as
visuospatial skills. Personality differences include greater aggressiveness in men.

In the area of sexuality, men and women differ in the strength of sex drive, interest in
casual sex, interest in visual sexual stimuli, styles of jealousy, sexual orientation,
interest in unusual forms of sexual expression, likelihood of engaging in coercive sex,
sexual risk taking, willingness to pay for sex, frequency of masturbation, sexual
response cycles, and the duration of reproductive capacity over the lifespan. Gender
differences show considerable overlap between the sexes, and their significance is
debated.

Many gender differences arise early in life. Boys are typically more active and
aggressive; girls are more interested in socializing. Boys and girls prefer different
toys, and both prefer to associate with children of their same sex. Sex-specific
interaction styles develop within these same-sex groups. Differences in other
cognitive traits emerge gradually during childhood.

Biological factors influence gender. These include genes that have evolved to help
men and women improve their reproductive success. A role for sex hormones,
especially during prenatal life, is illustrated by experiments on animals, by
observation of humans affected by endocrinological disorders, and by the study of
anatomical markers (such as finger length ratios) that are correlated with gender
traits.

Socialization influences gender. This can happen through the innumerable rewards
and punishments that children receive from parents and others. Imitation is also an
important mediator of gender learning.

A variety of cognitive developmental models stress the importance of children’s
thought processes in the development of gender. The understanding of gender
develops sequentially in young children. In sexual script theory, gender learning
involves the social negotiation of roles, such as those to be played by the man and
woman in heterosexual relationships.

Transgender people are those whose gender identity does not match their biological
sex. Transexuals are transgender people who seek to change their anatomical sex:
They may transition from male to female (M-to-F transexuals, or transexual women)
or from female to male (F-to-M transexuals, or transexual men). The change may
involve hormone treatment and sex-reassignment surgery, or just hormone treatment.
All transexual women and some transexual men have a childhood history of strong
gender nonconformity. They dislike the bodily changes induced by puberty and may
attempt to conceal them. They are usually homosexual in the sense that they are
sexually attracted to persons of the same birth sex as themselves. They usually do not
identify as gay, however, but rather as heterosexual individuals of the sex with which
they identify. Some transexual women are sexually attracted to women: Some or most
of these individuals have a different developmental history, in which their desire to
change sex develops out of a wish to incorporate the sex characteristics of their
preferred sexual partners (women) into their own bodies (autogynephilia).

Sex reassignment is a multistage process involving living for some period in the
identity of the other sex, followed by hormonal treatments and, sometimes, sexreassignment surgery. Genitals can be transformed into those of the other sex, but the
procedure is expensive and, particularly in the case of F-to-M reassignment, yields
imperfect results. Not all people who transition undergo genital surgery. Many
transexual women and men are satisfied with the results of sex reassignment and are
able to surmount the social and sexual challenges of post-transition life.
 Other transgender people do not seek sex reassignment for a variety of reasons. They
may not fully identify with either sex. Some believe that sex reassignment would be
unnecessary if society could be persuaded to abandon its obsession with the binary
nature of gender. All transgender people face discrimination and the risk of violence,
and many states fail to offer them specific protections.
Class Discussion Questions
1. You read a newspaper story about a family who is supporting their 8 year-old son who
is identifying and dressing as a girl. What interventions do you think would be most
appropriate for a child of this age (family therapy, hormones, surgery, counseling etc.)?
2. As a group, women and men differ in their performance on some cognitive tasks. Do
you think that learning or socialization contributes to these differences? Why or why not?
3. Gender development probably involves complex interactions between biology and
socialization. Did both types of influences affect the development of David Reimer (Box
4.3)? Why or why not?
4. How might individuals with conditions of intersexuality influence and enlighten our
definition and understanding of gender?
5. Transgender youth who lack social support are at increased risk of suicide and suicidal
ideation. In light of this, should all transgender youth who have access to hormone
therapy be permitted start on it? Does your answer to this question change when you
consider that most teens that identify as transgender are not “persisters” (see Box 4.5)?
Does your answer again change when you consider that some hormonal treatments cause
permanent anatomical changes (such as testosterone-mediated voice deepening)?
Videos to Facilitate Classroom Discussion
1. Human sexuality is complicated: A short video that discusses aspects of human
sexuality
https://www.youtube.com/watch?v=xXAoG8vAyzI
2. 22 people who didn’t have time for your gender expectations
http://www.buzzfeed.com/skarlan/22-people-who-didnt-have-time-for-your-genderexpectations#.cipZLPygb
3. 9 Things you need to know about being intersex
https://www.youtube.com/watch?v=CTYIjXSdZxA
Teaching Suggestions/Resources
1. Fine C. (2010). Delusions of gender: how our minds, society, and neurosexism create
difference. W.W. Norton & Company, NY.
2. Fooling the heteros: Vintage photos of drag queens
http://www.cvltnation.com/fooling-the-heteros-vintage-drag-queens/
3. Vaginoplasty: Male to female sex reassignment surgery
http://ai.eecs.umich.edu/people/conway/TS/SRS.html
4. Phalloplasty: Female to male sex reassignment surgery
http://www.savaperovic.com/ftm-penis-surgery.htm
5. How gender reassignment surgery works
http://www.livescience.com/39170-how-gender-reassignment-surgery-worksinfographic.html
6. Vintage photographs by Nadar of a young intersexed man (cut and paste link)
http://en.wikipedia.org/wiki/Hermaphrodite_(Nadar)
7. Huegel, K. 2011. GLBTQ: The survival guide for gay, lesbian, bisexual, transgender
and questioning teens, Second Edition. Free Spirit Publishing.
8. Boylan, J. F. 2004. She’s not there: a life in two genders. Broadway Books.
9. She’s a Boy I Knew (2007). A short film by Gwen Haworth
http://outcast-films.com/shes-a-boy-i-knew/
10. Link to IMDb list of films that address trans and intersex themes
http://www.imdb.com/list/ls051371235/
11. Website of the Intersex Society of North America
http://www.isna.org/faq/what_is_intersex
12. Gender Change: A 45 minute episode from Taboo
https://www.youtube.com/watch?v=0hjIeg1tE68
Recommended Reading
Bailey, J. M. (2003). The man who would be queen: The science of gender-bending and
transsexualism. Joseph Henry Press.
Baron-Cohen, S. (2004). The essential difference: Male and female brains and the truth
about autism. Basic Books.
Bertelloni, S. & Hiort, O. (Eds.). (2010). New concepts for disorders of sex development.
Karger.
Colapinto, J. (2000). As nature made him: The boy who was raised as a girl.
HarperCollins.
de Haan, M. & Johnson, M. H. (Eds.). (2003). The cognitive neuroscience of
development. Psychology Press.
Ellis, L., Hershberger, S., Field, E., et al. (2008). Sex differences: Summarizing more than
a century of scientific research. Psychology Press.
Eugenides, J. (2002). Middlesex. Farrar, Straus and Giroux. (Pulitzer Prize–winning
novel about a person with 5α-reductase deficiency.)
Fausto-Sterling, A. (2000). Sexing the body: Gender politics and the construction of
sexuality. Basic Books.
Geary, D. C. (1998). Male, female: The evolution of human sex differences. American
Psychological Association.
Hines, M. (2004). Brain gender. Oxford University Press.
Larsen, W. J. (1998). Essentials of human embryology. Churchill Livingstone.
Lippa, R. A. (2005). Gender, nature, and nurture (2nd ed.). Erlbaum.
Maccoby, E. (1998). The two sexes: Growing up apart, coming together. Harvard
University Press.
Mealey, L. (2000). Sex differences: Developmental and evolutionary strategies.
Academic Press.
Nanda, S. (1999). Gender diversity: Crosscultural variations. Waveland Press.
Pfaff, D. (2010). Man and woman: An inside story. Oxford University Press.
Rhoads, S. E. (2004). Taking sex differences seriously. Encounter Books.
Sax, L. (2005). Why gender matters: What parents and teachers need to know about the
emerging science of sex differences. Doubleday.
Key Terms
anal fold
androgen insensitivity syndrome (AIS)
anti-Müllerian hormone (AMH)
autogynephilia
cisgender
cloaca
cognitive
congenital adrenal hyperplasia (CAH)
cryptorchidism
disorders of sex development
double standard
gender
gender dysphoria
gender identity
gender role
genital swelling
genital tubercle
gonadal intersexuality
hypospadias
intersex
Klinefelter syndrome
metoidioplasty
Müllerian duct
natal
personality
puberty
real-life experience
sex chromosome
sex-reassignment surgery
sexual orientation
sexual script
sociosexuality
SRY
stereotype
transitioning
triple-X syndrome
Turner syndrome
transexual (or transsexual)
transgender (or trans)
transphobia
transvestism
urethral folds
Wolffian duct
urogenital sinus
X chromosome
XYY syndrome
Y chromosome