There are just two factors that can predict an illness, physical or mental. These are genes & enviroment.
In theory, mental illness is possible for every human being.
Sometimes individuals are genetically prone to illness, but the trigger is always “hidden” in the environment.
Some people can have a genetic predisposition to a certain mental disease, but without the environmental trigger they may never manifest it in their lifetime.
Anorexia, bulimia and binge eating can be caused by a social factor such as different beauty standards or by living in families that place a high value on looks.
Depression and bipolar can sometimes manifest in enviroments where high, unreachable expectations are set for individuals, while OCD can be caused by growing up in an authoritarian home.
War is a known trigger for PTSD and schizophrenia.
Mental illness is a total of factors including genes, environment, culture, education, social factors, family environment, unreachable beauty standards, traumatic events etc.