This reminds me of the anecdote about psychologist Sandra Bem's son, as told in her book An Unconventional Family. One day her four-year-old son, Jeremy, decided to wear barrettes in his hair to school. She wrote:
Several times that day, another little boy had asserted that Jeremy must be a girl, not a boy, because "only girls wear barrettes." After repeatedly insisting that "Wearing barrettes doesn't matter; I have a penis and testicles," Jeremy finally pulled down his pants to make his point more convincingly. The other boy was not impressed. He simply said, "Everybody has a penis; only girls wear barrettes."
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