Sexual Behviour Chapter Ten
Children prefer same sex toys even before they have been influenced to choose them.
Also seen in monkeys; male monkeys prefer wheels and sticks while female prefer dolls and plus
This suggests that part of the toy selection of male or female is somewhat biological
- Bad circumcision, doctors thought should be raised as a girl
- Genitals surgically altered and began Brenda
- Months later, Brenda developing nicely as girl, then downhill
- Brenda knew he should be a boy by grade two when he dreamed of growing up a man
- By 14, even after two years of female hormone therapy, he refused to live as a girl
- Killed himself 2004
- Exposed to an X0 chromosome instead of a XX or XY
- 1 / 2500 births
- We learned – the x chromosome is enough to develop a pretty normal person
- However the lack of a second sex chromosome does have an impact on fertility, growth and
hormone production and is associated with diabetes, osteoporosis, and cardiovascular diease.
- Have normal female genitalia, but ovaries are abnormal
- Intelligence is normal but have specific difficulties with spatial relationships and memory.
- Human growth hormone, female hormone therapy are used
- 1.79/1000 male births
- XXY genotype
- Born males but have low fertility and require hormone treatment to promote secondary makle
characteristics like facial hair
- Normal intelligence but difficulties usually in verbal skills
- Left handed more common which suggests it might affect brain lateralization or the localization
of specific functions
- Physical and behavioural correlates typically subtle and generally do not prompt parents to seek
- Boys appear to be physically within typical limits, taller and leaner, suffer from acne,have higher
risk for minor physical abnormalities of the eye, elbow and chest. Average iq scores.
- Fertile but more likely to produce sex chromosome abnormality - Males with XYY chromosomes have more male hormone, and more aggression. Super murder –
- Higher rate of antisocial behaviour, usually property crimes.
Androgen insensitivity syndrome (AIS)
- Disrupts normal development of the Wolffian system, abnormal androgen receptors
- Have XY genes and normal testes
- Lack of androgen receptors blocks anti-mullerian development but it is still releasing the anti
- Result is shallow vagina and no ovaries, fallopian tubes or uterus
- People with AIS are genetic males but have female appearance and strong female gender
identities. Many marry and have normal sexual behaviour for a female . occurs in 1 of every 50
women playing sports at international level
No hormonal activity is required to develop female external genitalia, a particular androgen, 5-alpha-
dihydrotestosterone, must be recognized by receptor sites for male external genitalia to develop
Congenital adrenal hyperplasia (CAH)
- Genetic females exposed to excess androgens, external genitalia become masculinised
- Fetus’ adrenal glands release elevated levels of androgens
- Males with CAM show few observable effects
- Clitoris enlarged, labia look similar to scrotum, no vaginal opening in some cases
- Describe themselves as tomboys, more male interest play and more likely to be lesbian or
Secondary Sex Characteristics – at puberty, additional hormonal events. Facial hair, deeper voice for
males and wider hops and breast development for females.
- Puberty has dropped from 16 to 12 due to things like obesity (accumulation of enough body fat
to support reproduction)
- When body fat is abnormally below, puberty is delayed
- Exposure to female hormones in cosmetics and animal tissue will trigger early puberty.
- Animal tissue contains type of estrogen called estradiol. Some places give animals hormone to
promote early puberty. If eaten, risk is 40% more
- Compounds found in plastics and cosmetics advance puberty in rats
- Onset of puberty, gonadotropin-releasing hormone (GnRH) released by hypothalamus. This
hormone initiates release of two gonadotropic hormones by the anterior pituitary gland, follicle-
stimulating hormone (FSH) and luteinizing hormone (LH).
- Boys males and females release this hormone but it has different effects - Stimulation by FSH and LH, the testes begin to produce additional testosterone and the ovaries
produces estradiol. The testes also produce small amounts of estrogen and the ovaries produce
small amounts of androgens including testosterone
- In males, extra androgens makes muscle, maturity of external genitalia, facial hair and
enlargement of the larynx which leads to deeper voice, regulates production of sperm.
- In females, estradiol produces breast growth, maturity of the external genitalia, maturity of
uterus and changes in fat distribution a