According to Dean Hamer, Ph. D and Peter Copeland, both New York Times Notable Book Award winners in their book “Living With Our Genes,” they have this to say about personality and temperament:
The dictionary definition of personality is, “The sum total of the mental, emotional, social, and physical characteristics of an individual.” It’s personality that determines the way you react to others, the way you communicate, the way you think and express emotions. These are the outward manifestations of basic traits that characterize a personality throughout life. Your thoughts, fears, hopes, reactions, behaviors, and dreams all come from your core personality.
Personality determines not just being but behaving. It influences how much you eat, drink, smoke, and sleep. Personality determines whether you are aggressive or shy, active or passive, who you are attracted to, and what you want to do with them of they’ll let you. It influences the amount of stress in your life, your physical health, and whether you live in pain or pleasure, in a sleepy haze or a high-octane blur. Personality is so complex that even though millions of people have walked the Earth, no two have ever been the seem. Just as the physical body has a seemingly unlimited variety, so does the personality that makes the body get up and go. Personality is what makes each person unique.
The latest research in genetics, molecular biology, and neuroscience shows that many core personality traits are inherited at birth, and that many of the differences between individual personality styles are the result of differences in genes. When you are conceived by two people, you are created from their genes. You are a product of generations of evolution, countless bits of information collected over millions of years, focused, narrowed, and refined until you were pushed out of the birth canal into the world. You look like the people in your family – and in some respects you feel and act like them, too. You have about as much choice in some aspects of your personality as you do in the shape of your nose or the size of your feet. Psychologists call this biological, inborn dimension of personality “temperament.” (pg 6,7)