Man=XY chromosomes, Woman=XX chromosomes.
Precisely.
“...they may have been said to have a different sex at birth.”
What someone “said”? NO, it’s what they ARE.
Since we can’t see chromosomes, we have to inspect the nether regions of the body.
If there is a tallywhacker there your sex is MALE!
It there is no tallywhacker there your sex is FEMALE!
Stop using the word “gender,” to identify sex. It is a word that is used in some languages that assign “gender” to objects, not the science of biology!
be running and hiding the rest of your life... Sad.