Influences on Infant Temperament

Children are born each day and each child is different from the next. Parents often notice individual characteristics in these small children. The question has been raised many times as to what affects these individual temperaments that make us all so different from each other. The nature versus nurture debate is often brought up. Instead of focusing on just one of these, we need to focus on both sides. Much of our individual temperament at birth is due to genetics (nature), but much of it is also because of our surrounding environment during our prenatal development (nurture).

Genetic Inheritance

In talking about where our temperaments come from, let us first look at our genetics. When a child is conceived, that child inherits 23 chromosomes from each parent (Lamb, Bornstein, Teti, 2002). Therefore, they inherit genetics from each parent. This genetic makeup can be a factor in the type of temperament that child has.

Studies on twins have been done where the researchers compared identical twins with fraternal, or non-identical twins. The identical twins share 100% of their genes, whereas fraternal twins only share around 50% of their genes, just as normal siblings do (Lamb et al., 2002). The studies found that the identical twins had similar temperamental attributes such as their activity level and their irritability. The fraternal twins did not show as many similarities to each other in their temperaments (Shaffer, 2005). From these studies, researchers have determined that heredity plays an important role in a person's individual temperament.

Environmental Influence

Another important factor in the temperament of infants is the environmental influence put on infants. In one 1992 study it was found that Chinese American and Japanese American babies were less perturbable, were better at soothing themselves, and experienced less change in arousal state than European American babies (Lamb et al., 2002).