Their psychological qualities such as intelligence, ability, aptitude, interest, taste, attitude, temperament, mental health, etc., also differ significantly. Similarly, groups also differ. Individuals differ because they reveal different personalities.
As G. W. All port, a noted psychologist, says, personality refers to “a person’s patterns of habits, attitudes, and traits which determine his adjustment to his environment”. Differences between personalities are obvious because each individual represents a unique combination of these physical and psychological traits or qualities.
What factors make every individual to develop his own physical and psychological traits? To make it more specific, what factors contribute to the development of human personality which is unique to every individual?