What we see is an overlap in the variability of genetic expression in a created biological matrix. It is a fallacy to assume that things with hair simply share common ancestry, even if they have similar genetic coding for hair. No, this is not the same as testing for heredity, because that is testing a species against itself. Cross-checking DNA sequences for human to chimpanzee similarity, for example, must make an assumption about the mechanisms in biology that WE DO NOT OBSERVE. This is all confirmed by the fact that there is absolutely no case in the natural world that can be pointed to that shows the type of changes to get hair in the first place, or an arm or an eye. Mutations are a problem for evolutionary thinking, not a solution. If you are convinced that is the answer, you should look into mutational load per generation for any species. There isn't enough time for any theoretical evolution before everything would start dying off from bad mutations, because bad mutations outnumber the "good" by orders of magnitude (like a million, so good luck with that "riddle"). This is a sin cursed world, and frankly, that's what we observe.