Temperament refers to an individual’s innate behavioral style and emotional reactivity, observable from early in life. It represents consistent differences in how people respond to their environment, largely independent of learned behaviors or values. The enduring question in psychology is whether this foundational aspect of human behavior is primarily shaped by genetic inheritance, environmental influences, or a complex combination of both.
Understanding Temperament
Temperament describes the “how” of behavior, distinguishing it from personality, which encompasses the “what” and “why” of actions. Temperament is considered a biological foundation upon which personality develops, a broader concept that includes both innate temperament and learned experiences.
Psychologists have identified several dimensions that characterize temperament, such as activity level, rhythmicity (predictability of biological functions), adaptability (ease of adjusting to changes), and intensity of reaction (energy of emotional responses). Other traits include responsiveness to stimuli, mood quality, distractibility, persistence, and attention span.
The Role of Genetics
Evidence supporting a genetic influence on temperament largely comes from twin and adoption studies. Twin studies compare identical (monozygotic) twins, who share nearly 100% of their genetic material, with fraternal (dizygotic) twins, who share approximately 50%. Identical twins consistently show greater similarity in temperament across dimensions like emotionality, activity, and sociability, compared to fraternal twins, suggesting a genetic contribution.
Adoption studies further support genetic influences by comparing adopted children’s traits with those of their biological and adoptive parents. Similarities between adopted children and their biological parents, despite separate rearing environments, point to genetic factors. These studies collectively suggest that individual differences in infant and child temperament are genetically influenced, with heritability estimates ranging from 20% to 60% of the variability within a population. Heritability, in this context, refers to the proportion of variation in a trait among individuals in a population that is attributable to genetic differences, rather than indicating how much a specific individual’s temperament is genetically determined. While specific “temperament genes” are not identified in a simple one-to-one manner, genetic predispositions contribute to individual differences through the complex interaction of many gene variations.
Environmental Factors at Play
Environmental factors significantly shape and modify an individual’s innate temperament. Early childhood experiences, including family environment and parenting styles, play a substantial role. For instance, a child’s temperament can elicit different responses from caregivers, influencing the child’s learning and social experiences and developmental outcomes.
Beyond family, broader environmental influences like cultural norms and unique individual experiences also contribute to temperament’s expression. Cultural values can influence how certain temperamental characteristics are expressed and perceived as adaptive. For example, shyness might be viewed more positively in some collectivistic cultures compared to individualistic Western cultures. Non-shared environmental factors, such as different peer interactions or schooling, also contribute to individual differences in temperament.
The Interplay of Nature and Nurture
Temperament is not solely a product of genetics or environment; instead, it arises from a complex interplay between both. This interaction is often described through concepts like gene-environment correlation and gene-environment interaction.
Gene-environment correlation explains how genetic predispositions can influence the environments individuals experience or seek out. Passive gene-environment correlation occurs when children inherit both genes and environments from their family that are aligned, such as musically inclined parents providing musical opportunities for their genetically predisposed child.
Evocative gene-environment correlation describes how a child’s inherited temperament can elicit specific responses from their social environment. For example, a child with an outgoing temperament may receive more positive attention, while a timid child might evoke different reactions.
Active gene-environment correlation, also known as niche-picking, involves individuals actively seeking out environments that align with their genetic tendencies, such as a child with a natural athletic ability pursuing sports activities.
Gene-environment interaction, on the other hand, refers to situations where genes express themselves differently depending on environmental conditions. For instance, certain genes might be activated or expressed differently in a child raised in an adverse environment compared to one in a supportive environment.
Temperament Over Time
While temperament shows stability, it is not entirely fixed and can be influenced by life experiences and developmental stages. Studies indicate that temperament is least stable during the first two years of life, becoming more consistent thereafter. Even with stability, individual rank-order positions on temperamental traits can change over time.
The concept of “goodness of fit” highlights how well a child’s temperament aligns with the demands and expectations of their environment, including parental caregiving styles. A good fit, where the environment accommodates a child’s temperamental needs, can lead to positive developmental outcomes and a stronger sense of self-regulation. Conversely, a mismatch can contribute to stress or behavioral challenges. Parents and caregivers can adapt their approaches and environments to better suit a child’s temperament, fostering a more harmonious fit and supporting the child’s development.