John C. DeFries (born November 26, 1934) is one of the world's leading behavior geneticists. His achievements include being President of the Behavior Genetics Association (1982–1983) and cofounder of the journal Behavior Genetics, as well as its co-editor (1970–1978). His awards include The Dobzhansky Award for Outstanding Research in Behavior Genetics (Behavior Genetics Association, 1992), Consulting Editor of the Journal of Learning Disabilities (1987–2002), Fellowships in the , Association for Psychological Science, and the American Association for the Advancement of Science, Section J (Psychology).