The difference between any one individual and another is attributed to both environmental and biological factors. A debate has existed over which aspect is more responsible for a person's identity, but modern interpretations recognize the importance of both influences on the development of unique individuals.
Nature and nurture are the two sources that modern psychology recognizes as influencing individual personalities. Even today, the importance of each is contested, as physical psychologists lean more toward nature, and behavior psychologists lean more toward nurture. From the nature side, heredity defines the physical reality of a body, which includes the brain and, thus, the conscious mind. Nurture is equally as significant, since health caused by heredity is irrelevant if nurtured in an unhealthy environment.
Despite being one of the oldest philosophical debates, the psychology field as a whole is aware of the important dynamic between nature and nurture, and how they work together to define the sense of self.
New research, such as the Human Genome Project, shows that the idea of disentangling the chaotic web between nature and nurture is a goal that ultimately yields little insight. Effort is being made instead toward determining whether specific genes can be identified that regulate the influence of particular environments.