Your personality has been sculpted by many hands. Your genes, your friends, the schools you attended, plus many other factors, will all have played a part in making you the person you are today. But when exactly did your own distinct character first begin to take shape? If you’re a shy person now, for instance, does that mean you were a shy child?

In all likelihood, yes. In fact, research suggests there are significant links between our behavioural tendencies when we’re just a few months old and our later personality. That isn’t to say that our personality was set in stone that early, but that the roots of who we are can be traced all the way back to our earliest days.

Psychologists who study babies usually refer to “temperament” rather than personality and one of the first ever investigations in this area was called the New York Longitudinal Study, launched in the 1950s, for which the wife and husband team of Stella Chess and Alexander Thomas began observing 133 children from their birth up to age 30, as well as interviewing their parents. Based on their findings, these researchers proposed that there are nine different facets of infant temperament, including activity level, mood and distractibility. They also noted that scores on different facets tended to cluster and, in a sign of a less politically correct age, they described three categories: “easy children”, “difficult children” and “slow to warm up” children.

Although infant temperament doesn’t completely forecast later personality, the two are certainly connected

Do these childhood categories presage later personality types? The New York study found some evidence that children categorised as easy or difficult at age three also tended to be categorised the same way in early adulthood, but the research didn’t examine links between child temperament and adult personality, as such.

In fact, for a long time psychologists studying infant temperament and those studying adult personality didn’t have a great deal to do with each other. Increasingly over the last decade or so, however, that has begun to change and although infant temperament doesn’t completely forecast later personality, the two are certainly connected.

Note that the scoring systems for infant temperament have changed over time. Today the original nine aspects of temperament are distilled into just three broad dimensions (unfortunately psychology labs often vary in the precise terms they use): “Effortful control” which describes things like the infant’s self-control and ability to focus (resisting, for example, the lure of a tempting toy); “negative affectivity, which as it sounds, refers to levels of negative emotion like fear and frustration; and “extraversion” or “surgency”, which is to do with activity levels, excitement and being sociable.

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