Genetics

• Genetics encompass the nature aspect of personality and implies that each individual is born with a set of genes that predispose him to certain traits and behaviors. A person's genetic makeup will determine his brain chemistry, which will determine how neurotransmitters like serotonin and dopamine function within the individual. These neurotransmitters can determine whether someone is reward-dependent, novelty seeking, impulsive or persistent. Mental disorders including schizophrenia and bipolar disorder have been linked to genetics and have a profound impact on personality.
  
  

Culture

• Every culture's values will result in prizing one set of personality traits and frowning upon another. For example, many Asian cultures are often oriented with family and achievement, and therefore produce people who are often determined, persistent and loyal; laid-back and free-spirited characteristics are discouraged. Beyond values, a culture's religion, customs and socioeconomic standing can affect personality. An individual from a third-world country is less likely to be materialistic than someone from Hollywood.
  
  

Childhood Home Life

• Various elements regarding an individual's home life as a child can shape personality. Whether both parents were in the home, there was a divorce, or the child was raised by a grandparent can all have a lasting impact. Children without a same-sex parent often lack a consistent role model, which can create identity issues. Birth order can also make a difference; first children are often energetic, middle children tend to be peacemakers, the last children can be attention seeking and only children tend to mature faster.
  
  

Experiences

• An individual's experiences in early life are considered a major factor in personality, but her experiences throughout life can continue to shape it. For example, someone genetically gifted with intelligence may have found that she performs very well in school and was rewarded for this. This could lead to a strong sense of confidence in her abilities. Traumatic experiences can also have an impact. An individual who was abused may become withdrawn, secretive and have trust issues.