The results showed that the heritability of AN was 0.56 within the DSM-IV narrow criteria and 0.31 within the DSM-IV criteria broad ones of the DSM-IV. The narrow criteria corresponded to the full DSM-IV criteria, while the broad criteria corresponded to the full DSM-IV criteria, except for amenorrhea. This distinction is particularly interesting because the current DSM-V no longer requires amenorrhea to meet the full diagnostic criteria. The result of the study shows that heredity can have a significant impact on the development of anorexia