well, we have to be careful here with terminology.
Gender has nothing to do with Chromosomes - Sex does. Gender's in your brain, mostly. I think you're
referring to when I said this:
I'd say that your Gender and Sex are the same, but the truth is that unless you've actually had it tested, you probably don't know what your chromosomes actually are, and they might be different from what you think they are.
When I said this I meant more specifically that there are many chromosomal disorders that are more common than people realize, and that some people who have them may not even know because they don't make you very different - XYY for example is one of the more common ones, and is found in around 1:1000 male births (and most people who do have it don't even know). XXY, or Kleinfelter's, is even more common, being pegged between 1:500 and 1:1000 male births.
So, Sex exists in a wide variety of forms outside of XX and XY. To further complicate things, there are also some disorders like Androgen Insensitivity Syndrome, which affect how testosterone is absorbed by the body. With Complete AIS, One can be a biologically XY person that presents and grows and goes through puberty exactly as someone with XX chromosomes usually would, including having a womb and being able to carry children. I've even read a paper of one XY woman giving birth to an XY daughter (I'm not sure if AIS is hereditary).