[ObscureScience]

I don't believe that is true (but I am certainly outside of my expertise). As far as I understand it, sex chromosomes (specifically the Y chromosome) are responsible for genitalia differentiation, but the relevant genes of the chromosome needs to be expressed for it to happen. Whether it's the Y chromosome itself that is inactive, or genes on the other chromosomes that supress it I have no clue about.

[davorak]

There is genetic transfer between X and Y so you can have XX and still have male genital[1].

No expert but I thought there was a few to several cases along these lines.

To my understanding chromosomes are never responsible for anything, they are a container for genes, and some genes are likely to live on particular chromosomes, so talking about chromosomes being responsible is never 100% correct, so a bad level of abstraction when talking about corner cases.

[1] https://en.wikipedia.org/wiki/XX_male_syndrome