This is consistent with what I have read in the recent medical literature. I am also skeptical about the "adult-onset" gender dysphoria. Their excuse is that they had been enduring for years until they finally figured our what they had been suffering. So maybe that was the case with people who grew up decades ago. But if someone does not realize their gender dysphoria well into their adulthood today, I would be very suspicious.
Hopefully, it will become easier to sort out the real ones from the imaginary ones.