How does sexual orientation develop?

Thirty-five years ago, on May 17, 1990, millions of people around the world suddenly became "healthy." On that day, the World Health Organization (WHO) removed homosexuality from the list of human diseases.

Until then, same-sex love was considered a kind of "mental illness." Those affected were often locked up in mental institutions or prisons and "treated" with electric shocks or questionable psychotherapies.

Today, it is completely clear that homosexual, bisexual, or transsexual people are not and never have been sick, says Prof. Dr. Klaus M. Beier, Director of the Institute for Sexology and Sexual Medicine at the Charité Hospital in Berlin. Human sexuality is characterized by its diversity.

"It's now clear: No one chooses their sexual orientation . It's fate, not choice. Under the influence of sex hormones during puberty, what experts call the "sexual preference structure" develops. And from adolescence onward, it's programmed into the individual's gender orientation, what the body schema of the desired person is, and what sexual interactions one would like to have with that person."

After this developmental phase in adolescence, the respective sexual preference remains stable, says Beier. "It develops in adolescence and then remains stable throughout life, despite the desire some people have for their sexual orientation to change, for example, due to social pressure to be like everyone else."

Non-heterosexuality is made a problem in many places

Universal human rights include the right to freedom of sexual orientation. Sexuality is and always has been diverse. It is neither a fad nor, for example, limited to particularly liberal societies .

"According to the data we have, same-sex orientation occurs at a rate of approximately three to five percent in the population, and this applies across cultures. Human sexuality cannot be handled any other way. It is characterized by this diversity—and cannot be handled any other way," says sexologist Beier. Therefore, it is wrong to judge or even condemn someone based on their sexual orientation.

Nevertheless , the sexual orientation of individuals polarizes entire societies . This sometimes leads to their exclusion, discrimination, and persecution. Homosexuality, for example, is punishable in at least 67 countries; in seven, same-sex sexual activity is even punishable by death.

Almost half of all countries worldwide where homosexuality is prohibited are in Africa. Only 22 of the 54 official African states have legalized homosexuality. In some countries, it is punishable by imprisonment; in four countries – Mauritania, Nigeria, Somalia, and South Sudan – the death penalty is threatened; these are governed by Sharia, Islamic law.

How does sexual orientation develop?

A simple question, one that has no simple or definitive answer. There is no single cause for sexual orientation, but rather various genetic and hormonal explanatory models and sociocultural interpretations.

"According to current knowledge, this is a multifactorial process. No one has yet been able to identify any single factor that could be the cause of one person being same-sex oriented and another being opposite-sex oriented," Beier said.

It can therefore be assumed that a complex interplay of biological and social factors is responsible for the development of sexual orientation.

Biological influencing factors

The biological factors influencing the development of sexual orientation that have been studied include genes, i.e. heritability, as well as (prenatal) hormones and chemical substances.

Sexual orientation is not innate, meaning it is not hereditary. Family and twin studies do show a clustering of homosexuality in some families. However, the genetic markers found are not very conclusive; there is no single "homosexuality gene."

Hormones and other chemical substances

Hormones such as testosterone and chemical substances such as pheromones may also be responsible for the development of sexual orientation. Pheromones are scents that influence sexual behavior, for example.

Studies show that male pheromones stimulate hypothalamic activity in both heterosexual women and homosexual men—but not in heterosexual men. The hypothalamus is a gland in the diencephalon that influences our instinctual behavior and sexual functions.

Social influences on sexual orientation

Dolls and clothes for girls, tools and cars for boys – typically female or male toys have no influence on sexual orientation. The same applies to upbringing.

While some people may not fully realize their actual sexual orientation until later in life, sexual preference generally does not change over the course of life.

"We have very strong evidence that this isn't possible. There are follow-up studies on sexual orientation. There were these unfortunate 'conversion attempts' in same-sex-oriented men. This was attempted in a larger study in the United States in the 1970s. Without any success. Strong evidence that sexual orientation is very stable."

While sexual orientation develops during puberty, the development of gender identity begins in childhood and is complete for most people by the age of five or six, according to Prof. Beier. From this age, children can "see themselves in their future gender and thus make assumptions about their future as a man or a woman."

Once sexual orientation is established, it doesn't change. Not even through "seduction" or early sexual encounters. "There's nothing to that," says sexologist Beier. "Important evidence of this: There are many people who had same-sex sexual encounters in their youth, but who are not same-sex oriented."

Whether children experience support or rejection from their parents is crucial for identity development. Children and adolescents who experience strong rejection often develop comparatively lower self-esteem. If parental rejection relates to the child's sexual identity or orientation, it can lead to depression and suicidal thoughts.

Sexuality is diverse

Especially in societies where sexual minorities are marginalized and persecuted, a prejudice-free debate about sexual diversity is very important, says the director of the Institute for Sexual Sciences and Sexual Medicine at the Charité in Berlin.

From a scientific perspective, no sexual orientation is considered a disease or "unnatural." What is tolerated, or what is considered "normal" or "unnatural," is determined by social norms . These norms can change significantly depending on time and context. But human nature does not change.