A cheap clone who genocided the original and then interbred with his women would be expected to be a genetic train wreck. That is always what the facts show.
Neanderthals are the originals. Homo Sapiens is a bad copy. If you didn't know better you'd think somebody built in deliberate safeguards to keep the two from intermixing and when they are activated we call them birth defects. Always the Neanderthal genes are the good ones. The Sapiens genes are just a life support system for a pair of testicles and a very impressive spearchucking capacity.