Sex (and hence "boyness" and ""girlness") is neither "assigned" at birth nor "imposed" by society. It is "observed." And, in this age of routine sonograms, is usually observed before birth.
We saw --- observed --- detected --- recognized --- our firstborn son's sex as "male," hence his gender pronouns as "masculine," his destiny as "man," months before he was born.
Hint: it's the extra ornament.
(BTW this particular pic was not his, but his nephew's. For illustration, not documentation.)
Distinguishing simply between "male" and "female" is on its way to being a hate crime.