Behavioral genetics is the field of study that examines the role of genetics in the behavior of animals (including humans). Often associated with the concept of "nature versus nurture," behavioral genetics is highly interdisciplinary and includes contributions from biology, genetics, ethology, psychology, and statistics. Behavioral geneticists investigate the inheritance of behavioral traits and frequently use twin studies or adoption studies as tools in humans, or breeding, transgenesis, or gene knockout techniques in animal genetics. Psychiatric genetics is a closely related field.