First of all, those aren't analogies which state x is like situation y. They're laws of nature. Incest just isn't only taboo, it abuses the whole point of sexual reproduction which provides genetic diversity so unwanted traits don't stay with every individual.
Humans have the ability to defy nature, like with GMO you like. For better or worse. When you decide which life is sacred it desensitizes you to what makes humans human. Many serial killers start first with torturing animals. Americans once thought African humans were worth a fractional part of a white human. What makes humans different from other animals is human caring. Otherwise Michael Vic wouldn't have been arrested. It is one thing to kill because of self defense and quite another to murder based off your palette. It's quite petty and selfish. Animals don't have the capacity to violate nature, we do. Bring a child to a petting zoo and pet a calf. Slit it's throat in front of the child and let it die in their hands the proper kosher method of purity. Watch the child's sorrow, yet watch your mouth salivate as you bite into your veal. And you say I have the screw loose.
