GxE or gene environment interaction refers to the way genes and environment combine to alter the risk of impairments to children's health and development. One example is the way the MAOA enzyme mediating the environmental risks of child maltreatment. Such evidence has helped shift science from 'nature versus nurture' to 'nature and nurture'. The ideas are similar to the diathesis-stress model to study the relationship between a non-biological or genetic predisposition (diathesis) with the environment and life events (stressors) to produce disorders such as schizophrenia.