By Steven Schlozman, MD, Gene Beresin, Executive Director and David H. Rubin, M.D.

Posted in: Grade School, Infants & Toddlers, Podcast, Pre-School, Teenagers, You & Your Family

Topics: Child + Adolescent Development

Intro music written and performed by Dr. Gene Beresin.
Outro music arranged and performed by Dr. Gene Beresin.

We have all had the experience of either knowing or parenting siblings that seem quite different from one another—in appearance, skills, talents, opinions and personalities. When these variations represent positive characteristics, such as proficiency in a sport or a good sense of humor, we readily accept and celebrate children’s individuality. However, when they are perceived as negative qualities, which vary in the eye of the beholder but might include, for example, excessive shyness or a short temper, we ask ourselves what happened to have caused this. In the case of parents, “What did we do differently with this one?”

Take one of nature’s favorite jokes: to bestow upon a parent a first-born who sleeps and eats in a pleasantly predictable pattern, is fascinated by new experiences and who greets surprises with laughter and curiosity. The parent thinks, “Easy as pie, what’s all the fuss about? Let’s have 10 more.” Then enters the first sibling, one who is colicky, wants to be fed in a pattern that can surely inspire a new Las Vegas table game, is offended by every visitor to the home, and assumes that all “new news” is bad news. How can this be?

The particular differences emphasized above demonstrate the presence of temperament—the nearly “predetermined,” innate aspects of each individual’s personality that will persist throughout his or her life at some level. They are a collection of “default” preferences and reactions that come with each baby, preset at the stork factory. The 1950s marked a period where a group physicians and scientists—Alexander Thomas, Stella Chess, Herbert G. Birch, Margaret Hertzig and Sam Korn—began to study the ways that temperament could be observed and measured, and how it persisted across the lifespan. Some of the characteristics of temperament, which include rhythmicity (how predictably and patterned babies eat and sleep), response to novelty (whether a baby tends to experience new things as threatening, interesting, or amusing), activity level (couch potato versus always in motion), distractibility and general mood, will be observable at age 3, age 30 and age 103. They are core parts of who we all are.

Temperament is now understood to be 60% genetic, meaning that 60% of it is written into our very DNA. It is humbling to learn just how many of our qualities are actually inherited as predispositions.  Height and eye color are easy ones, but how about our inclinations toward spirituality or  political party affiliation? Our toy preferences as children? All of these have been shown to be moderated, in part, by our genetic code.

We understand this through the study of twins. Identical twins essentially share the same genetics, and if they are able to be raised together, they also have an environment in common.  Despite their best efforts to do otherwise, identical twins raised together will be more similar to each other, even in personality, than any other two people on the planet. When tragically separated at birth, identical twins reveal the differences that are entirely due to having been in different environments. Those differences, with respect to temperament, however, tend to be surprisingly few.

So what does all of this mean for parents? Are children’s outcomes, for the most part, “fixed” from the beginning? Certainly not! As we mentioned, only about 60% of temperament is genetic. That leaves a considerable remainder, 40%, to experience and learning. What’s important to remember is that parents can make the most of that 40% that is subject to influence and environment by understanding the 60% that children arrive with. This poses the task of balancing parenting practices that prove beneficial to all temperaments—those characterized by structure, consistency, empathy, collaboration and role-modeling—with some degree of customization.

Take the two siblings in our first example. The first-born, while predictable and generally open to new experiences, may prove to be bold in all undertakings. Parents may need to temper appropriate encouragement to experience new things with frequent warnings and caution, as this first baby is predisposed to find all novelty welcoming. Conversely, the second baby will not likely need reminding to exercise restraint, but will benefit instead from a more gradual exposure to new experiences, paced in such a way so as to not overwhelm him or her. Parents need to encourage children to explore, but must guide them individually in how to best master situations based on their given temperament. It’s important to emphasize that every possible success and happiness is just as available to the second child as to the first, but if either were to be raised as if he or she were the other, both would be vulnerable to disappointment and failure. Our genes determine only what we will never be (i.e., 6’7” tall for many of us), but they say nothing about what we will be. They are the boundaries of the sandbox, but have no hold on the great sand castles we can build within it.

In sum, parents can study and learn about their children’s temperaments to help them grow “to love the model they drive,” or, put in another way, to be comfortable in their own skin. While parents may universally aspire for their children to obtain certain core skills, traits and values, the way each child achieves them will be partly dictated by his or her temperamental starting points.