Transgender children are no more or less likely than other children to conform to gender stereotypes in how they dress and play, suggesting they have a strong sense of identity from an early age, according to a study published on Monday.
All young children tend to favour the toys and clothing typically associated with their gender, researchers at the University of Washington concluded from a study of hundreds of American and Canadian children aged between 3 and 12.
The project marked the first time that transgender children - those who do not identify as the gender they were born with - had been studied from such a young age, according to the researchers.
It comes amid a fierce debate in several Western countries over the number of children being referred to gender identity clinics and sometimes going on to have hormonal treatment in adolescence that affects how they develop.
"Our data thus far suggest that the act of transitioning probably isn't affecting gender identity one way or the other," said Kristina Olson, a psychology professor who leads the TransYouth Project at the University of Washington.
The project studied 317 trans children alongside 189 of those children's siblings and another 316 non-trans children.
The study concluded that children "develop a strong sense of identity at an early age, that this identity is not necessarily determined by the sex assigned at birth, and that children may hold onto this identity even when it conflicts with others' expectations".
The trans children in the study had undergone a "social transition", whereby people change their pronouns, clothing and hairstyles, a contentious subject in some Western countries.
In October, the governor of Texas said authorities were investigating the case of a seven-year-old whose father had gone to court to try to stop his ex-wife allowing the child to socially transition from boy to girl.
The number of children and young people referred to Britain's Gender Identity and Development Service rose from 678 in 2014-15 to 2,590 in 2018-19, underscoring the scale of the rise in demand.
More than two-thirds of those children were born female, giving rise to concerns over whether some girls who would in the past have been seen as "tomboys" are now under social pressure to transition.
Similar rises were recorded in clinics in Toronto and Amsterdam between 2006 and 2013.
The TransYouth Project, launched in 2013, purports to be the largest long-term research project into trans children globally. Monday's study comes from its first wave of data.
The researchers noted several limitations to their results: all children had transitioned with the support of their parents and were American or Canadian. A majority had wealthy, white, highly-educated parents.
"We do not know how the results may have differed if we had studied children who identify as transgender but have not yet transitioned or children who live in less supportive environments," it said.