Can a nerdy child grow up to be an aggressive tycoon? Can a childhood bully develop into a mild-mannered librarian?

Psychologists have debated for a hundred years whether our personalities develop mainly in early childhood or continue to change and grow throughout our lives. Sigmund Freud was the first to state that personality is formed in early childhood and basically stays the same throughout adulthood.

Now research seems to back up Freud’s contention.

A new study, which appears in the February issue of the Journal of Personality, followed 103 kids for 19 years, starting when they were age 4 and ending when they were in their 20s. To get an initial sense of the personalities of the preschoolers, researchers surveyed both teachers and parents when the children were ages 4, 5 and 6. Based on the observations of their parents and teachers, the children were identified as having one of three personality types: overcontrolled, undercontrolled or resilient.

Over the course of the study, the researchers had parents fill out questionnaires every year up until the children were 10, and then again when the children reached the ages of 12, 17 and 23.

Overcontrolled types were shy, undercontrolled kids were aggressive, and resilient children were in-between. “Overcontrollers control their emotions too much,” explains Jaap Dennissen, lead author of the article. “So they are less able to act ‘natural’ and ‘spontaneous.’ Because they are so slow to warm up, they are seen by others as shy,” he adds.

Undercontrollers were kids who tended to act impulsively and to act out frustration by being aggressive to others. These are the kids who become bullies and derive feelings of power and self-esteem from it. In the study, such kids were still bullies and aggressive at the age of 23, but had moderated the aggression somewhat.

Resilient types were those kids who seemed most well-adjusted; good at moderating their emotions. They could bounce back from adversity and they tended to be more mature in their conduct. These children grew up to be adults who did not act impulsively or compulsively.

The study found that as all three types of children grew into adulthood, they kept their personalities: the overcontrolled kids became overcontrolled adults; the undercontrolled kids became undercontrolled adults; and the resilient kids became resilient adults.

However, undercontrolled kids seemed to become a bit less aggressive, as mentioned before, as they reached adulthood, perhaps due to the many societal forces that disapprove of aggressive behavior, and sometimes punish it.

The study did not venture a theory as to how we get our personalities. Some psychologists, such as Freud, believe we form our personality as we go through stages of early childhood development. In other words, our environment shapes us. During the Oedipal period, for example, we can develop an Oedipal complex which may cause women to be attracted to father figures and men to mother figures.

Others psychologists, such as Hans Eysenck and Raymond Cattell, have completely negated the effect of environment and believe we inherit our personalities. They conjectured that sources of traits such as shyness or conscientiousness are found in our DNA or parts of our brain.

My own research has convinced me that there is both a genetic contribution, and an environmental source. However, life’s experiences play the bigger part. If you are told from early childhood that you are valuable, you will feel valuable; if you are told you are worthless, you will undoubtedly have a problem with self-esteem. Or if, as a child, you see an older brother or sister being praised for a certain trait, such as kindness, you will be more likely to imitate it.

To a great extent we become what we live and we live what we become. And, according to recent research, personalities remain more or less constant from childhood, when they are set.

This research to some extent confirms Freud’s personality theory.