The external genitals continue to develop after the internal ones have formed.
Or it may later turn out that a newborn with the external genitals of a boy has a female's ovaries inside.
But I think if the external genitals are really masculinized, you work it out with the family.
Gender has far more to do with other important structures than external genitals.
Other than external genitals, there are few physical differences before puberty.
When she first met him she wondered about his gender, for he had no external genitals.