Part of each child's development is predetermined by the type of genes with which he or she comes into the world. This will determine their temperament, part of their personality, their physical characteristics and much of their abilities to perform under the stable or unstable conditions presented by Erikson. Due to the environment in which the child is raised, certain genes can be turned on and off, which could make a child more or less likely to live a good life according to Erikson's stage theory of development. Genetics and biology could also explain the development of morality, because the ability to be moral sometimes depends on the psychological state of the individual. Cognitive impairments can sometimes affect the development of