there are long regions on the Y chromosome that are very similar to the X chromosome, which would make the analysis difficult: https://en.wikipedia.org/wiki/Ps

there are long regions on the Y chromosome that are very similar to the X chromosome, which would make the analysis difficult: https://en.wikipedia.org/wiki/Pseudoautosomal_region https://en.wikipedia.org/wiki/Pseudoautosomal_region