What should a researcher do if he or she finds something unexpected in the DNA of a human research participang during an experiment? That was one topic of the recent Personal Genomes meeting at Cold Spring Harbor Laboratory, says Nature News' Erika Check Hayden. What are the ethics of revealing "nasty surprises" to people, Hayden asks. As sequencing an increasing number of genomes becomes more common, this question will come up more and more, Hayden says.