Vegan Thanksgiving. Sounds like an oxymoron, doesn’t it? But that might be until you learn the truth about turkey: Most conventional birds have been inbred to the point that they can’t even reproduce naturally. And many are stuffed full of chemical fat-inducing hormones and pesticides—even before you stuff them. The idea of giving up the bird comes with backers. Doctors say we should reduce meat consumption for optimal health. Scientists recently recommended halving meat consumption to reduce environmental impact. And vegans point out that giving up animal products positively contributes to the fight against global warming: Livestock and poultry production tipped the scales in 2009, claiming responsibility for 51% of…