Eunuchs: Whether a eunuch has a penis depends on the type of castration that was performed.
Men who get a sexual realignments surgery have penises. Don't believe me? We could arrange for one to insert their thingie into one of your holes. Then you can let us all know what you think.
note:
A DNA sample of a transgender person will show their biological sex, meaning the chromosomal makeup they were born with (XX for female, XY for male), which may not align with their gender identity; a DNA test cannot directly determine someone's gender identity as it is a complex biological and social construct not solely based on genetics; however, research is ongoing to explore potential genetic links to gender dysphoria.
But as time goes on we will discover more unsettling realities. If you meet up with a transgendered whatever, before sex would you require a dna sample?