In cats, black fur color is caused by an X-linked allele, while the other allele at this locus causes orange color. The heterozygous allele is tortoiseshell. Normally, only females have the tortoiseshell phenotype because
a male inherits only one allele of the X-linked gene for hair color
multiple crossovers on the Y chromosome prevent orange pigment production
only males can have Barr bodies
genetic imprinting prevents males from inheriting tortoiseshell traits from a mother