Current and former members of the Mormon Church are calling for an end to the practice of asking children as young as eight intimate and sexual questions during annual interviews by church officials.
"I suffered with a lot of guilt, because I did things we weren't supposed to do," 27-year-old David Sheppard told the Victoria Derbyshire programme.
"They teach us masturbation is just below murder, and I felt like I was some sort of sexual deviant or pervert for doing it."
Mr Sheppard, from London, was brought up within the Mormon Church.
From the age of 12 he was interviewed alone in a room by a bishop for what is known as a "worthiness interview".
The Mormon Church is divided into wards, similar to parishes, with the bishop being the spiritual head of a local ward.
The worthiness interviews, the church says, are designed to prepare children and teenagers spiritually and ensure they are obeying the commandments.
They often start around a child's eighth birthday, when Mormon children are baptised, and then again at the age of 12.
They are meant to be carried out at least annually thereafter into adulthood.
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The most controversial element of the interviews relates to something known as "the law of chastity", though some bishops choose not to ask questions about sex.
In the Mormon Church - officially known as the Church of Jesus Christ of Latter-day Saints - sex outside of marriage, pornography and masturbation are banned.
Mr Sheppard says between the ages of 16 and 19 he had "a few girlfriends" with whom he had intimate relationships, without having sex.
"I decided to confess to what I had been doing and it resulted in six hours of interrogation," he adds.
"They asked questions like, 'Did you touch her?' and 'Did you make her orgasm?'.
"They even tried to get me to give up the names of the girls so that she could be dealt with.
"At one point during the interview I felt sick from anxiety and asked to leave and go to the toilet but they wouldn't let me do that.
"I felt as though I had a total loss of control."
The interviews are conducted in a closed room, one-on-one with an older male bishop, unless the child or teenager requests another person to be present.
They have caused controversy in the US, and now in the UK - where the church says there are 190,000 believers - a campaign to stop the practice is gaining ground.
"As a person, the bishop was a good man," says Mr Sheppard.
"He was just doing what he was told to do, but I think the interviews should be consented to by the child, and they should have someone else in the room.
"The bishops aren't even trained to do this sort of thing."
The Victoria Derbyshire programme has also heard first-hand accounts of a woman who says that as a teenage girl she was told not to use contraception, and a man who says a bishop spoke to him about "praying the gay away".
The Mormon Church said it "condemns any inappropriate behaviour regardless of where or when it occurs".
It added: "Local church leaders are provided with instructions regarding youth interviews and are expected to review and follow them.
"A caring, responsible spiritual leader plays a significant role in the development of a young person by reinforcing the teaching of parents and offering spiritual guidance."
The church said their guidebook makes clear that children under 12 "are not asked about chastity, and parents are invited to be with their child".
Stephen Blomfield, from Bedford, was on the church's Stake High Council until 2011 and is still a member of the Mormon Church. He did not conduct interviews but acted as an advisor to people who did.
But he also now believes the interviews must be scrapped.
"At my first youth programme aged 12 or 13," he says, "we were told kissing was bad, and touching was bad.
"So I adopted huge feelings of guilt, because I had already kissed girls."
Masturbation and pornography, he adds, were described as "satanic".
Mr Blomfield - whose father was a bishop - says, in his experience in the 1980s and 90s, how intrusive the questions were during interviews depended on the bishop.
"Some leaders asked really explicit questions... whereas others never asked unless you confessed first.
"The interviews could be really embarrassing, exposing and stressful."
Mr Blomfield now has children of his own, but says he has informed his local church they will not be interviewing them.
"If they want to, they need to discuss it with me first or make sure I'm present.
"I'm of the opinion the interviews should be scrapped.
"They've been around since the religion began, but they should have never been set up.
"They're intrusive and ask private questions, and I think they're the reason some Mormons can suffer shame- because they can't live up to the standards set."
Watch the BBC's Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News Channel in the UK.