It would be logical to assume that individuals consistently backcrossing with MD, for instance, would acquire a MD morphology, and yet, our combined data support the opposite finding, where hybrids with MD morphology all have WTD Cytb haplotypes, and a preponderance of WTD neutral SNPs, and vice versa for hybrids with WTD morphology exhibiting a preponderance of MD genetic material. The gene discussed is MT-CYB; the disease is Menkes disease.