Of the 11 percent who expressed varying degrees of "gender non-contentedness" at the beginning, only 4 percent still reported these feelings by the end of the study period. In real terms, that means 305 pre-teens began adolescence with feelings of gender confusion, and only 111 felt the same way by their mid-20s -- a decrease of almost two-thirds.

"The results of the current study might help adolescents to realise that it is normal to have some doubts about one's identity and one's gender identity during this age period and that this is also relatively common," the researchers concluded. Researchers sourced their data from Tracking Adolescent's Individual Lives Survey (TAILS), an ongoing, longitudinal, general population cohort study that began in the year 2000.

At the outset and then at three-year intervals, TAILS participants were asked to respond to the statement, "I wish to be of the opposite sex." They could respond "Not True", "Somewhat or Sometimes True", or "Very True or Very Often".

According to the Dutch research team, "Three developmental trajectories of gender non-contentedness were identified: no gender non-contentedness (78%), decreasing gender non-contentedness (19%), and increasing gender non-contentedness (2%)."

While members of the 2% cohort felt less comfortable with their gender by age 25, the entirety of the 19% cohort had desisted from feelings of gender incongruity by study's end. "At the sixth assessment wave (around age 25), none of these individuals reported experiencing gender non-contentedness anymore," the team observed.

The team also found that gender non-contentedness did not take place in a vacuum.

"Individuals with an increasing gender non-contentedness more often were female and both an increasing and decreasing trajectory were associated with a lower global self-worth, more behavioural and emotional problems, and a non-heterosexual sexual orientation," they wrote.