Genetics & Environment on Personality PDF

**[Evolutionary and genetical theories on personality:]** 1\. review the goals of **behavioural genetics** 2\. discuss **genotype-environment correlations** 3\. define heritability and environmentally 4\. contrast **adoption** studies and **twin studies** 5\. compute **heritability** and **envi...

**[Evolutionary and genetical theories on personality:]** 1\. review the goals of **behavioural genetics** 2\. discuss **genotype-environment correlations** 3\. define heritability and environmentally 4\. contrast **adoption** studies and **twin studies** 5\. compute **heritability** and **environmentally** from the findings of twin studies 6\. discuss **criticisms** of **adoption** studies and **twin** studies 7\. consider the **heritability** of diverse **personality** characteristics, **temperaments**, and **personality disorders** **\***human example of intersexual selection = preference Combative or competition **Behavioural genetics:** Immediate influences examines, something within us at the present. (Ex: genes, neurochemical) *What are the goals?* 1. Determine [individual differences] caused by genetic factors vs. Environmental Equation: VP = VG + VE VP = variation in personality within population VG= genetic factors variation VE= environment factors in variation **\*\***behavioural genetics cannot apply to individuals only population. Why? Genotype-environment correlations **Type of correlations:** 1. **Passive** genotype-environment correlation a. Parents [passively] provide gene-conductive environments which allows expression of children's genetic predisposition 2. **Reactive** genotype-environment correlation b. [Actively] gene conductive environment occurs which allows expression of a genetic predisposition 3. **Active** genotype-environment correlation c. [Niche] picking d. [Create]/seek a gene-conductive environment that encourages the expression of a gene 2. Identify [specific genes] that give rise to particular personality characteristics a. Ex: Gene D4DR on chromosome 11 contributes to individual differences in sensation seeking (ex: speeding, bad sexual habits...) i. How? Dopamine dysfunction which requires more risks to experience dopamine 3. Identify [environmental factors] that contribute to individual differences b. Ex: non-shared environmental influences are greater than shared environments **Heritability and environmentality:** **Heritability**: proportion of phenotypic variance that is attributable to genotypic variance **Environmentality**: the proportion of phenotypic variance that is attributable to variance in environmental factors. How to assess heritability/environmentality? 1. **Adoption studies** (most used) a. Correlation between adopted children scores and their biological scores b. Correlation between children and their adopted family Results: personality traits passed on by biological parents **Criticism**: Studies do not correct for selective placement. Selective placement = adoptive parents are similar to biological parents. 2. **Twin studies :** (more powerful than adoption studies) Monozygotic twins = 100% Genes identical Dyzygotic twins = 50% genes identical Problem: not enough sample Result = heritability influences personality greatly (should not exceed value =1) **Criticism**: Do not correct for equal environment assumption. MZ twins are treated more similarly than DZ twins by environment (parents). Therefore cannot say they inherit more personality. Equal environment assumption = two individuals exposed to identical environmental factors. \*\* studies do not account for this. If environment managed very similar correlation results are not as significant **Findings of personality attributes:** *What personality characteristics are inheritable?* *Ex: FFT (five factor taxonomy)* **FFT:** How these factors inherited? Average of 0.5 inheritability Agreeableness : 0.42 due to genetics factors (42% variance) Conscientiousness: 0.49 Extroversion: 0.54 Neuroticism: 0.48 Openness to experience: 0.57 [Conclusion: 50% of variance in personality due to genetics and 50% to environment]. **Temperaments:** Temperaments are personality associated at the first year of life. Believed to have high heritability. 1. Activity level: expends physical energy (tempo=slow, rigorous= high activity)- extraversion 2. Emotionality: physically aroused level -neuroticism 3. Sociability: prefers to be with others or alone -- extroversion / agreeableness *\*\*highly heritable* Heritability of personality disorders: - Narcissistic- high - Schizotypal -- high - OCD -- lowest - Borderline, avoidant, antisocial -- medium (0.67-0.69) Heritability of characteristics of psychopathy: High in: - Carefree - Coldheartedness - Fearlessness - Impulsive nonconformity - Machiavelliansm (enjoying manipulations of others) - Stress immunity (not being stressed when discussing how they've killed someone) **What these suggests:** Cannot fix anything and are all biologically determined. Biological determinism must be questioned. Avoid trap. Personality disorders and psychopathy is inevitable. Most heritability fall between 0.4-0.6. Most at level of 0.5 (**average effect size = 0.47)** across many studies. Personality equally determined by environment and genes.