Gaga is a man.
Has the Y chromosome.
Don't need to see its dick to know for sure.
If you can't tell that's a tranny at first glance, you need to investigate moar.
Castratos have that range too.
A castrato (Italian, plural: castrati) is a type of classical male singing voice equivalent to that of a soprano, mezzo-soprano, or contralto.
Castration before puberty (or in its early stages) prevents a boy's larynx from being transformed by the normal physiological events of puberty.
As a result, the vocal range of prepubescence (shared by both sexes) is largely retained, and the voice develops into adulthood in a unique way.
Research yourself.