When you read a dramatic report of a survey

telling about bullying or marijuana use or pretty much anything self-reported, remember that people like to joke.

In a 2003 study, 19 percent of teens who claimed to be adopted actually weren't, according to follow-up interviews with their parents. When you excluded these kids (who also gave extreme responses on other items), the study no longer found a significant difference between adopted children and those who weren't on behaviors like drug use, drinking and skipping school. The paper had to be retracted. In yet another survey, fully 99 percent of 253 students who claimed to use an artificial limb were just kidding.