Becker was one of the first economists to branch into what were traditionally considered topics belonging to sociology, including racial discrimination, crime, family organization, and drug addiction (see rational addiction). He is known for arguing that many different types of human behavior can be seen as rational and utility maximizing. His approach can include altruistic behavior by defining individuals' utility appropriately. He is also among the foremost exponents of the study of human capital. Becker is also credited with the "rotten kid theorem."