Ahmad seems like any other teenager in the Afghan capital, Kabul. He goes to school, hangs out with friends, and lives at home with his parents.

But the 18-year-old is hiding a dangerous secret that could get him imprisoned or killed: He is homosexual.

Homosexuality is a taboo topic in Afghanistan, a socially and religiously conservative country. Many consider homosexuality un-Islamic and immoral, and gay men can be imprisoned by the state or killed by their family members in so-called honor killings.

"Homosexuality is seen as a disease in Afghanistan," Ahmad, who does not reveal his real name because he fears for his safety, tells RFE/RL. "It is seen as a sin in Islam, and many people think homosexuals should be executed."

It is this fear that has prevented Ahmad from revealing his sexuality to his parents and friends. His family of seven expects him to marry a woman and follow traditional social norms.

"I realized I was gay when I was around 15 years old," Ahmad says in a phone interview. "All my friends were talking about girls, but I realized I was not interested in girls. Slowly I began to realize that I was only attracted to men. It was scary because I felt like an alien and I couldn't even talk to anyone about it."

The gay community in Afghanistan lives in secret and its members often lead double lives -- heterosexuals in public and homosexuals in private.

No official punishment has been meted out for homosexuality since 2001, according to Human Rights Watch (HRW).

But Afghan law is vague on homosexuality, which is not outlawed but may be punished on a local level by unofficial Shari'a courts or mishandled as any of a number of distinctly different crimes. Extramarital sex is punishable by five to 15 years in prison under Afghan law. But under Shari'a law, the punishment for sex outside marriage can be death.

In a report issued in February, HRW said gay men "risk arrest, prosecution, and violence from their families, the larger community, and the government."

"Afghan law provides no protection against discrimination or harassment on the basis of sexual orientation or gender identity," the report added.

'Can't Live Like This'

But that has not eliminated the fear of punishment for coming out.

"If my family found out [I'm gay], I would be kicked out from home and disowned," Ahmad says. "That's the best-case scenario. The worst case would be my family would kill me so they can restore their honor and get rid of the shame that I brought them."

Ahmad says gay men meet each other in shopping centers, parks, and gyms. They also meet in private in underground cafes, apartments, and in cars during the night.

Ahmad is a practicing Muslim, but he says his sexuality has made him question his religion. "I know that homosexuality is against Islam, but I'm always asking myself, 'Why would God make me and others like this?'" he says.

Ahmad says he wants out of Afghanistan and has plans to seek asylum in the United States. "I can't live like this," he says. "I'm in constant fear and I cannot be myself without endangering myself."

Despite the overwhelming public stance against it, homosexuality exists in Afghan society -- and in some forms it is even widespread. The ancient practice of "bacha bazi" -- literally, dancing boys -- is common among wealthy and powerful men who exploit underage boys as sexual partners. The victims are often orphans or boys from poor families as young as 10.

The crime for "pederasty" -- sexual activity involving a man and a boy -- is punishable with "lengthy imprisonment" under Afghanistan's Penal Code, but it frequently goes unenforced.

Yet young boys are sometimes dressed as girls and made to perform. The boys are often sexually abused and raped. The practice of bacha bazi has reportedly spread since the fall of the Taliban, who declared it un-Islamic.

'Huge Cost'

Nemat Sadat, an Afghan-American gay-rights campaigner living in Washington, is working to change attitudes toward homosexuality in Afghanistan.

Sadat was born in Afghanistan but raised in the United States. He returned to Kabul in 2012 to work at the American University of Afghanistan (AUAF).

A year later, Sadat became the first Afghan gay man to publicly come out. But he lost his job at the AUAF and was pressured by the authorities to leave the country, he said.

"I was forced to resign from my post as professor of political science and was threatened to be put on trial and given a life sentence in prison or the death penalty if I remained in Afghanistan," he says.

"It came at a huge cost, as most of my friends and relatives blocked me out of their lives, claiming that I brought them and the entire community of Afghan and Muslims dishonor by revealing my sexuality," Sadat says, adding that he no longer has contacts with most of his family.

'Fake Life'

Razaq, a 21-year-old from the western Afghan city of Farah, is another gay man living in constant fear.

"My friends and family don't know I'm gay," he says by phone. "I live a normal life, but I have also a secret life that I have to hide from everyone I know. If people find out that I'm gay, it would be a disaster."

Razaq is at an age when many men marry in Afghanistan, and he says he has no choice but to adhere to the social norm.

"I'm 21 and soon I will have to marry a woman," he says. "There's no other option. Almost every gay man I know is married. If you're 30 years old and you're not married, people will start to think something is wrong with you. So we live a lie, a fake life, because we have to."

Razaq has had several sexual relationships with other men. He says he met them in secret locations in the city -- underground guest houses and cafes.

Razaq says gay men are wary of police, who he says frequently demand money or sexual favors if they come across a gay man. "We have to do it -- otherwise they threaten to tell our families," he says.

"Many pretend it [homosexuality] doesn't exist in Afghanistan," he says. "But everyone knows there are gays in Afghanistan, like everywhere else in the world."