Although Irving Gottesman, PhD, and his colleagues first brought it to psychiatry research in 1987 (in McGuffin et al1), the term endophenotype originated 21 years earlier, in entomology. In their studies of grasshoppers, John and Lewis2 noted that the insects鈥� external appearance (or exophenotype) provided few clues to understand their geographic affinities; rather, they speculated that the insects鈥� internal, microscopic constitution (or endophenotype) would reveal more answers. But while the term may have arisen outside of psychiatry, there is no question that, with respect to health research, psychiatry now owns it. For example, a PubMed search reveals that, of more than 4100 published articles linked to the term endophenotype, more than 90% focus on psychiatric conditions and their underlying neural constructs.