Is temperament determined by genetics?
Temperament is a complex trait influenced by a combination of genetic variations and environmental factors, with scientists estimating that genetics account for 20 to 60 percent of these behavioral characteristics.
Overview
Temperament encompasses behavioral traits such as sociability, emotionality, activity level, attention level, and persistence. These characteristics represent a spectrum of common traits, each potentially advantageous in specific circumstances. Temperament is generally consistent, particularly throughout adulthood.
The Role of Genetics
Studies of identical twins—who share 100 percent of their DNA—compared to their non-twin siblings suggest that genetics play a significant role in temperament. Identical twins typically exhibit very similar temperaments, even when raised in separate households.
Temperament does not follow a clear pattern of inheritance, and there are no specific genes that dictate individual temperamental traits. Instead, it is influenced by:
- Polymorphisms: Many common gene variations (potentially thousands) combine to influence temperament.
- Epigenetic changes: DNA modifications that do not alter the DNA sequence likely contribute to these traits.
- Brain communication: Many identified genes involved in temperament regulate communication between cells in the brain.
Specific Genetic Associations
Research has linked various gene variants to specific temperamental traits:
- New experiences: Variants in the DRD2 and DRD4 genes.
- Self-discipline and carefulness: Variants in the KATNAL2 gene.
- Sociability: Variants affecting the PCDH15 and WSCD2 genes.
- Introversion: Certain MAOA gene variants, particularly in specific environments.
- Anxiousness or depression: Variants in genes including SLC6A4, AGBL2, BAIAP2, CELF4, L3MBTL2, LINGO2, XKR6, ZC3H7B, OLFM4, MEF2C, and TMEM161B.
Environmental Influence
Environment plays a critical role by influencing gene activity. For example, children raised in adverse environments, such as those involving violence or abuse, may experience the activation of genes that increase the risk of impulsive temperamental characteristics. Conversely, a positive environment, such as a safe and loving home, may lead to the activation of a different set of genes, potentially fostering a calmer temperament.