Yes, you can come out at any age, 17 is still quite young. I don't know the statistics, but aware or not, many here came out as adults (37 for me).
The idea of a 4 year old child telling their parents they are definitely the opposite gender is quite rare, but the press love it, so it's what cis-gender get fed.
Children or adolescents get told they're too young and 'it's just a phase'. Older people get told 'you never showed it as a child', we can't win [emoji853].
Forget the averages, you are an individual. X
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