Role of genes in behaviour ERQ

Role of genes in behaviour

Genes influence biological processes that can affect behaviour, but their expression is shaped by environmental factors (epigenetics and gene-environment interaction).

Epigenetics

The process by which gene expression is modified by environmental factors without changing the DNA sequence, often through chemical markers.

Aim of Weaver et al. (2004)

To study how maternal care influences stress response in rats through epigenetic regulation of the glucocorticoid receptor gene.

Method of Weaver et al.

Experimental study comparing pups of high-licking/grooming vs low-licking/grooming mothers; measured cortisol levels and GR gene expression.

Results of Weaver et al.

HLG pups had lower stress and higher GR gene expression; LLG pups had higher cortisol and anxiety; cross-fostering reversed the effect.

Conclusion of Weaver et al.

Maternal care alters gene expression (epigenetics), which influences stress-related behaviour; environment can shape gene expression.

Strengths of Weaver et al.

Experimental control; shows clear causal link; key evidence for epigenetics in behavioural development.

Limitations of Weaver et al.

Animal study → limited generalizability; artificial lab conditions; long-term human parallels unclear.

Aim of Caspi et al. (2003)

To examine how the 5-HTT gene influences the likelihood of developing depression after experiencing stressful life events.

Participants in Caspi et al.

847 New Zealanders from a longitudinal birth cohort study.

Method in Caspi et al.

Participants were genotyped for the 5-HTT gene and surveyed about stressful life events and symptoms of depression.

Results of Caspi et al.

People with two short 5-HTT alleles were more likely to become depressed after stressful events; two long alleles = lower vulnerability.

Conclusion of Caspi et al.

The 5-HTT gene influences sensitivity to stress; genes don't cause behaviour directly but affect vulnerability.

Strengths of Caspi et al.

Large sample; real-life application; strong evidence for gene-environment interaction.

Limitations of Caspi et al.

Correlational study; self-reported stress; ethical concerns with genetic labeling.

Weaver and Caspi on genes and behaviour

That genes influence behaviour, but their effects depend heavily on environmental factors—through epigenetics or gene-environment interactions.

Gene-environment interaction (GxE)

A concept where genetic predisposition affects how individuals respond to environmental experiences, and behaviour only manifests when both factors are present.

Weaver et al. on environment in gene expression

Maternal care altered the expression of the stress-related glucocorticoid receptor gene in rats, affecting their stress responses—an example of epigenetics.

Caspi et al. support gene-environment interaction

People with the short 5-HTT allele were more likely to develop depression, but only after stressful life events—genes increased vulnerability, not direct causation.

Studies challenge genetic determinism

They show that genes do not rigidly determine behaviour; instead, they influence the likelihood of behaviour depending on life experiences and context.

Model of behaviour supported by studies

The biopsychosocial model, which considers biological, psychological, and social influences on behaviour, rather than relying on genes alone.

Importance of timing in gene expression

Weaver shows early-life environment impacts gene expression long-term, while Caspi shows genetic vulnerability in response to life stress during adulthood—genes may influence behaviour differently across the lifespan.

Key takeaway about genes in behaviour

Genes influence behaviour through complex, dynamic processes, and their effects are probabilistic, not deterministic.

Conclusion of the ERQ

Genes influence behaviour by affecting biological systems, but expression depends on environmental interaction — behaviour is not genetically determined, but genetically influenced.