2.1.17 Genetic influences

Genetic Influences on Development Including Gene-Environment Interactions

Genetics plays a significant role in human development, influencing physical and behavioural characteristics from conception to old age. The complex interplay between genes and the environment, known as gene-environment interactions, shapes an individual’s development and can affect the expression of genetic potential.

Genetics can influence the development of physical characteristics such as eye and hair colour, height, and facial features. Studies have also found genetic contributions to various medical conditions such as cancer, heart disease, and diabetes. For example, certain genetic variants have been identified as increasing the risk of developing conditions such as Alzheimer’s disease, and specific genetic mutations have been linked to conditions such as cystic fibrosis and sickle cell anaemia. Additionally, genetics plays a role in cognitive and behavioural development, influencing factors such as intelligence, personality, and mental health. For example, twin studies have shown that heritability estimates for cognitive abilities such as intelligence are around 50-70%. However, it is important to note that genetics alone do not determine an individual’s cognitive abilities, as the environment also plays a role.

Moreover, genetics also plays a role in the development of behavioural characteristics such as aggression and mental health disorders such as depression and anxiety. Studies have found that certain genetic variants are associated with an increased risk of developing conditions such as depression and schizophrenia. For example, a study found that individuals with a specific variant of the serotonin transporter gene were more likely to develop depression in response to stress.

However, it is important to note that genetics alone do not determine an individual’s characteristics and behaviours, as the environment also plays a significant role.

Gene-environment interactions involve the interplay between genetic makeup and the environmental conditions in which an individual develops. For example, a genetic predisposition to a certain health condition may only manifest if the individual is exposed to certain environmental factors such as diet or pollution. This can also be observed in the case of behavioural characteristics, where a genetic predisposition to a certain behaviour may only manifest if the individual is exposed to certain environmental factors such as childhood experiences or stress.

Moreover, gene-environment interactions can also occur at different stages of life, and different environmental experiences can have different impacts depending on the timing of the exposure. For example, early childhood experiences can have a greater impact on development than experiences later in life, and certain genes may be more or less responsive to environmental factors depending on the stage of development. This is known as the differential susceptibility theory which posits that some individuals may be more susceptible to the effects of negative environments but also more responsive to positive environments.

It’s also important to note that gene-environment interactions are not limited to a specific gene or environment, but rather a complex interplay between multiple genes and multiple environmental factors. This highlights the importance of considering both genetic and environmental factors in understanding human development.

In conclusion, genetic influences on development and gene-environment interactions are complex and multifaceted, and research in this field is ongoing. Understanding the interplay between genes and environment can have important implications for understanding individual differences in development and for developing interventions to improve health and well-being.

References:

(1) Belsky, J., & Pluess, M. (2009). Beyond diathesis stress: Differential susceptibility to environmental influences. Psychological bulletin, 135(6), 885-908.

(2) Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., … & Poulton, R. (2003). Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene

(3) Plomin, R., DeFries, J. C., Knopik, V. S., & Neiderhiser, J. M. (2016). Behavioral genetics. Routledge.

(4) Scarr, S., & McCartney, K. (1983). How people make their own environments: A theory of genotype-environment effects. Child development, 54(2), 424-435.