One distinction I make among people is between humanists and transcendentalists on the question of where rights come from.
- A transcendentalist would likely say either that they come from god (e.g., "endowed by their creator") or that they just are; they are embedded in the universe. They are part of natural law.
- A humanist (as I am) would say rights are conventional. People in a culture decide what rights they each have, not necessarily through formal action (as in the Bill of Rights) or legislation but more often by what collectively feels right to us, which is some complicated mix of genetic and epigenetic factors and synapses caused by our parents and friends and what we see on the news. Since people vary in all these factors, it is not surprising that some of us care about animal privacy and some do not.
And as a mild biological determinist, I can't hold it against the transcendentalists that they are so horribly wrong. They can't help being wrong, just as I can't help feeling right on this issue.