1 Psychology and human development1.12 Stages of human development
1.12.9 Sexual development
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Written by Resident Doctor Committee · Published
Dimensions of sexuality
Dimension | Meaning |
|---|---|
Sexual orientation | The pattern of people to whom someone is sexually attracted |
Sexual behaviour | What a person does, and with whom |
Sexual identity | The label a person uses, or their choice not to use one |
Gender identity | The inner sense of being female or male, shown in early childhood by accurate self-labelling |
Gender role | Outward gender-typed behaviour |
Each dimension develops separately and is distinct from biological sex. Gender identity is also distinct from gender constancy.
Transgender is now a broad, identity-based umbrella term that covers non-binary and fluid identities. Unlike the older clinical definition of transsexualism, it does not require distress.
Kohlberg's stages of gender development
Kohlberg's cognitive-developmental theory describes three stages in order.
Stage | What the child understands | Age |
|---|---|---|
Gender identity | The child labels themselves as a boy or a girl | About 2 years |
Gender stability | Gender persists over time | About 4 years |
Gender consistency or constancy | Gender survives changes in appearance and activity | About 6 to 7 years |
Puberty
Reactivation of the hypothalamic-pituitary-gonadal axis drives puberty.
Feature | Girls | Boys |
|---|---|---|
First sign | Breast development | Testicular enlargement |
Average onset | About 11 years | About 11 to 12 years, about a year later than girls |
Precocious puberty | Onset before 8 years | Onset before 9 years |
Disorders of sex development
17-beta-hydroxysteroid dehydrogenase type 3 deficiency is a 46,XY disorder of sex development in which the testes cannot convert androstenedione to testosterone.
Babies have undervirilised genitalia at birth, virilisation appears later, and the testosterone to androstenedione ratio is low.
Influences and clinical practice
No parenting pattern or family structure determines sexual orientation, and no single gene explains it.
Sexual orientation is not a mental disorder, and the International Classification of Diseases, 11th revision (ICD-11), places gender incongruence under sexual health.
Stigma, rejection and victimisation raise rates of depression, self-harm and substance use in sexual minority young people, and family acceptance protects against them.
Sexualised behaviour in children needs safeguarding assessment when it involves coercion, a marked age or power gap, distress or unusual sexual knowledge.