Whether you're a nice person isn't just about your life experiences: Chemicals appear to play a big role, too. Your kindness, or lack of it, depends in part on whether your brain has the right kind of receptors for the hormones behind affection, scientists find. Researchers asked hundreds of subjects about their perspective on the world—whether they saw it as a rewarding or dangerous place, and whether they saw people as basically good or bad.
The scientists also examined the DNA of the subjects. They found that even if people had a negative worldview, they were kind and giving if they had the "nice" receptor genes, LiveScience reports. Those genes, which result in part from just one DNA base pair, "allow you to overcome feelings of the world being threatening and help other people in spite of those fears," says a researcher. "We aren't saying we've found the niceness gene, but we have found a gene that makes a contribution." (Read more kindness stories.)