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Genetic Influences on Lifespan, Health and Psychological Traits
Introduction
Genetics play a crucial role in shaping human lifespan, health, and psychological attributes. While environment and lifestyle choices are significant factors, research shows that our genetic makeup can predispose us to certain health outcomes, behavioural tendencies, and emotional patterns. This essay explores how genetic and phenotypic factors interact in determining personality and longevity. It also examines key personality traits such as neuroticism, psychoticism, extraversion, and social desirability, alongside attitudes like pessimism and optimism, to understand how inherited traits shape both physical and psychological wellbeing.
Genetic Influence on Lifespan and Health
Studies in behavioural genetics suggest that roughly 25% of the variation in human lifespan is due to heritable genetic factors (Deelen et al., 2019). Genes related to metabolism, immune function, and resistance to disease can influence longevity. For instance, variants of the FOXO3 gene are associated with longer life expectancy, as they promote cell protection and stress resistance (Willcox et al., 2008). However, lifestyle factors such as diet, exercise, and exposure to stress can modify these genetic effects, illustrating the complex relationship between genes and environment.
Genetic predispositions also contribute to the likelihood of developing chronic diseases like heart disease, diabetes, or certain cancers. The presence of particular alleles can increase risk, but their impact often depends on environmental triggers. For example, a person with a genetic tendency toward high cholesterol may avoid heart problems through a healthy diet and regular exercise, showing that genes set probabilities rather than certainties.
Phenotypic and Genetic Relationship Between Personality and Lifespan
Personality traits, observable aspects of behaviour and emotion, have both genetic and phenotypic bases. Twin studies consistently show heritability estimates of 40–60% for major personality dimensions (Bouchard & Loehlin, 2001). These traits can influence lifespan indirectly through lifestyle choices and coping styles. For example, conscientious individuals tend to live longer due to healthier habits and better stress management. Conversely, individuals with high neuroticism may experience greater stress and anxiety, increasing the risk of cardiovascular problems or depression, which can shorten lifespan.
The phenotypic expression of personality depends on both genetic predisposition and environmental shaping. While genetics may set the potential for a certain temperament, factors such as upbringing, social context, and life experiences refine how those traits manifest. Therefore, lifespan and health are best understood through a gene–environment interaction model, rather than genetic determinism alone.
Personality Dimensions: Neuroticism, Psychoticism, Extraversion, and Social Desirability
Eysenck’s model of personality identifies three main traits influenced by genetics: neuroticism, psychoticism, and extraversion (Eysenck, 1990).
Neuroticism refers to emotional instability and sensitivity to stress. Individuals with higher levels of neuroticism often report more anxiety, mood swings, and health complaints, possibly due to increased physiological stress responses.
Psychoticism describes traits such as aggression, impulsivity, and lack of empathy. High psychoticism has been linked to genetic variations in dopamine regulation, which affects behaviour control and emotional regulation.
Extraversion involves sociability, assertiveness, and positive affect. Extraverted individuals tend to have stronger social networks and may benefit from better mental health and longer lifespans due to increased social support.
Social desirability, the tendency to present oneself favourably, is often linked with conscientiousness and emotional control. Although partly influenced by upbringing, research suggests a moderate heritable component related to self-regulation and social cognition (Furnham, 2008).
Pessimism and Optimism
Optimism and pessimism also show moderate heritability. Genetic studies indicate that about 25–30% of the variation in optimism levels can be explained by genes (Plomin et al., 1992). Optimistic people tend to cope better with stress, maintain healthier lifestyles, and show stronger immune responses. In contrast, pessimism correlates with higher levels of stress hormones and a greater likelihood of developing depression or physical illness.
These traits highlight how psychological factors, shaped by both genes and environment, can directly influence physical health and mortality. The interaction between genetic predisposition and personal choices determines how these traits manifest and impact wellbeing.
