This means that defining humanity by genetics opens up lots of opportunities for abuse. One is that humans genetically altered by adaptation to their increasing exposure to chemicals may, if the gene-centered classification is passed into law, be officially classed as nonhuman and thus legally used as slaves. Another possibility is that the gene-centrists are looking forward to the discovery of some animals with completely "human" genomes, allowing them to have sex with them without officially being considered zoophiles (and of course to jail people married to or having relationships with genetically altered people by legally classing the latter as "animals"). The next Hitler may be a gene-centrist hiding his/her own genetic alteredness and self-classifiying as human (even in the official sense) despite classifying everyone else equally genetically altered as "animal".
So it is obvious that lots of powerful organizations, both companies looking forward to legal slave labor as well as more jail inmates to use as cheap workforce, zoophiles, and political movements wanting to demonize as a way to stir up and gain power, have a common interest in promoting a gene-centered definition of "human".