Genetics Flashcards
(22 cards)
What is the nature of a gene?
Genes are made of DNA, which provides the blueprint for the structure and function of the human body, including behaviour.
What is gene regulation?
The process of switching genes on and off.
Resuls in differential gene expression.
What does gene expression refer to?
When a gene is activated
Leading to physiological processes that can affect behaviour.
How are genes regulated?
Internal: Hormones, chemicals, other genes.
External: Environment (stress, diet).
Epigenetics Defined
Changes in gene expression without altering DNA structure.
Affected by environment (stress, nutrition, caregiving).
Reversible and heritable
Two Types of Epigenetic Marks
DNA Methylation: Silences genes.
Histone Modification: Loosens or tightens the DNA structure, controlling access to genes.
Behavioural Genetics
Combines genes + environment.
Traits like IQ, aggression, criminality unlikely from one gene.
Twin, adoption, family, molecular studies used to research heritability.
Twin Studies
MZ twins: 100% genes, high concordance = high heritability.
Used to isolate genetic vs environmental effects.
Bouchard et al. (1990) – Minnesota Twin
To investigate the influence of genetics and environment on intelligence and other traits using twins reared apart and together.
Bouchard et al. (1990) – Minnesota Twin Method
Longitudinal twin study.
Over 100 sets of MZ
Twins raised together and apart.
50+ hours of psychological and physiological testing to compare
Bouchard et al. (1990) – Minnesota Twin Results
High similarity in IQ, even when raised apart
Only slightly lower than those raised together
Bouchard et al. (1990) – Minnesota Twin Conclusion
Strong genetic component in intelligence. Environment also plays a role but is less significant than genetic influence.
Bouchard et al. (1990) – Minnesota Twin Strengths
Large sample size
High concordance even when raised apart
Bouchard et al. (1990) – Minnesota Twin Limitations
Self-selected sample via media → sampling bias
Assumes MZ twins raised together had identical environments
Couldn’t control for pre-study contact between twins
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics
To examine whether maternal sensitivity buffers the epigenetic impact of maternal depression on infant stress response.
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics Method
128 mother-infant pairs.
Depressive symptoms assessed via self-report.
Cortisol levels measured pre/post stress (non-responsive play).
Methylation of stress-related genes assessed from cheek swabs.
Maternal sensitivity coded via behavioural observation.
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics Results
High maternal sensitivity = lower infant cortisol + no increase in methylation.
Low sensitivity + high depression = increased methylation and higher cortisol.
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics Conclusion
Maternal care moderates the epigenetic impact of maternal depression on infant stress physiology.
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics strengths
Applies animal epigenetic findings to humans
Real-world implications (interventions in postnatal care)
Conradt et al. (2016) – Maternal Sensitivity & Epigenetics limitations
Relatively small sample
Self-reported depression → possible bias
Difficult to establish causality
Scarr & McCartney (1983) – Niche Picking Hypothesis
Genes influence preferences for environments (niche-picking).
Chosen environments enhance trait development (e.g. intelligence).
Genotype shapes environment → environment feeds back on phenotype.
How can niche-picking hypothesis be applied?
Explains how genetically similar individuals (e.g. twins) may have similar IQ even if raised apart.
Integrates genetic predisposition with environmental shaping.
