I voted 35 - 50% as I find many hybrids offer color, variations and intensity thereof never to be found in species! Nature regulates life, what is not compatible cannot be created. If weak or not resistant life will be short and hardly reach maturity (blooming stage for plants). A horse and a donkey can mate, but the resulting mules cannot reproduce (sterile). That is one of nature's ways of controlling unfavourable reproduction. If really not compatible, mixing usually doesn't work at all. If nature allows a life to be created there must be a valid reason. Think of all the races among human beings, when intermixed are they not somewhat "humanoid hybrids"?