DNA testing has been in the news lately, thanks to the raid on the FLDS compound in Eldorado, Texas where authorities don’t know which children belong to which parents. We find out what DNA is, how it defines us, and how DNA testing works. Dr. Timothy Bestor is Professor of Genetics and Development at the College of Physicians and Surgeons at Columbia University Medical Center. Dr. Brian McCabe is Assistant Professor of Physiology and Cellular Biophysics at the College of Physicians and Surgeons at Columbia.