Hi. Do you eat meat?  I am vegan and don't eat or use anything made from animals
I do eat meat, but I completely respect vegans and vegetarians. I recently read that some vegans don't even keep pets because they view it as oppressive.
That's true - we say "ethical vegan" and are against the use of animals for anything! 
My brother in law is vegan for environmental reasons. Is that also being an ethical vegan?
not only follow a vegan diet but extend the philosophy into other areas of their lives, and oppose the use of animals for any purpose. Another term is "environmental veganism", which refers to the avoidance of animal products on the premise that the industrial farming of animals is environmentally damaging and unsustainable.
Well-planned vegan diets are regarded as appropriate for all stages of life, including during infancy and pregnancy, by the American Academy of Nutrition and Dietetics, Dietitians of Canada, Australian National Health and Medical Research Council
Ethics of eating meat
The question of whether it is right to eat animal flesh is among the most prominent topics in food ethics. People choose not to eat meat for various reasons such as concern for animal welfare, the environmental impact of meat production ("environmental vegetarianism"), and health considerations. Some argue that slaughtering animals solely because people enjoy the taste of meat is morally wrong or unjustifiable. Vegans often abstain from other animal products for similar reasons.
Ethical vegetarians and ethical vegans may also object to the