Teenagers who question their biological gender often have friends who have become transgender.

More than one in five teenagers and young adults who suddenly questioned their gender identity after puberty had one or more friend who ‘came out’ as transgender in the same time frame, according to a study of their parents.

Coming out as potentially transgender made their children more popular within their friendship group, almost two-thirds of parents aware of their child’s popularity said.

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Teenagers who question their biological gender often have friends who have become transgender (stock image)

US researchers surveyed 254 parents of children with gender dysphoria - the ‘emotional distress’ of feeling you are a different gender to that you are born with - which came on suddenly after puberty.

In almost 90 per cent of cases, the children were reportedly second, third or fourth within their friendship group to question their gender.

The study, published in the journal PLOS One, raises concerns that gender dysphoria could spread through groups of friends.

This has already been seen in friendship groups for eating disorders, depression and drug use.

Dr Lisa Littman, the author of the research from Brown University School of Public Health, said: ‘Of the parents who provided information about their child’s friendship group, about a third responded that more than half of the kids in the friendship group became transgender-identified.

‘A group with 50 percent of its members becoming transgender-identified represents a rate that is more 70 times the expected prevalence for young adults.’

In April to September last year, more than 760 British teenagers aged 15 to 17 were referred to the Gender Identity Development Service at the Tavistock and Portman NHS Foundation Trust.

In 2017-18, the trust, which is the only facility specialising in child gender identity, received an extra £2.8 million ($3.5m) in funding to cope with rising demand.

To explore the influence of friends and social media, researchers gave US parents of gender-confused teenagers and young adults a detailed questionnaire.

One parent said their child had seen a ‘great increase in popularity’ by identifying as transgender, adding: ‘Being trans is a gold star in the eyes of other teens.’

Another said their child had become ‘untouchable’ to bullies, as teachers are ‘all at pains to be hot on the heels of any trans bullying’.

In April to September last year, more than 760 British teenagers aged 15 to 17 were referred to the Gender Identity Development Service at the Tavistock and Portman NHS Foundation Trust (stock image)

The US study recruited parents from websites for those critical of the ‘transgendering’ of young people.

However 88 per cent believed transgender people deserved the same rights as everyone else.

The parents said children questioning their gender had an average of 3.5 friends in their group who also identified as transgender.

The results show 21 per cent of parents said their child had one or more friends who came out as transgender around the same time.

One in five reported an increase in their child’s social media use around the same time as their gender dysphoria, with parents suspecting YouTube ‘transition’ videos about trans people had influenced this.

Others suspected children had taken their ‘coming out’ speeches verbatim from online, sounding ‘wooden’ or as if they were reading from a script.

Among the gender-confused children and young adults, aged 11 to 27, more than half of parents said they wanted surgery to change their sex, with almost two-thirds saying their children wanted to take powerful hormones such as oestrogen or testosterone.

The study concludes: ‘The description of cluster outbreaks of gender dysphoria occurring in pre-existing groups of friends and increased exposure to social media/internet preceding a child’s announcement of a transgender identity raises the possibility of social and peer contagion.’

Dr Littman added: ‘It’s going to take more studies to bring in more information, but this is a start.’