Lecture 7 Flashcards
(28 cards)
1
Q
What are the genetics of behaviour?
A
- Heredity provides us with two kinds of characteristics: common to all human beings e.g language, and those genes that distinguish us as individuals
- Science of genetics concerned with both
- Discipline of behavioural genetics concerned with the second = individual differences : focus is on what accounts for variability among people with respect to a given characteristic and not on causes of a particular mean value for that characteristic in a population
2
Q
What is behaviour genetic?
A
- Method for quantifying genetic and non-genetic effects
- Behaviour genetics uses twin and adoption studies to investigate the contribution of genes and environment to a variety of behaviours, traits and abilities
- These studies tell you about genetic and non-genetic components of phenotypes
- Basic tenet is looking at similarity of pairs of relatives who differ in their genetic relatedness
- If pairs of relatives who share a greater proportion of their genes are more similar than pairs of relatives who share less genes = assumption is due to genes
3
Q
What are the methods of studying genetics?
A
- Family studies: examine if a trait runs in families by comparing frequencies of traits/disorders = consistent with genetic explanation but this method cannot disentangle gene/env factors
- Twin studies: Identical and fraternal (100% vs 50% shared DNA)
- Adoption studies: adoptive parents provide env, bio parents share genes
4
Q
What is twin study methodology?
A
- Look at similarity of pairs of identical twins and compare to pairs of non-twins Compare correlation, and with algebra = can separate genetic and env influences
- MZ - genes+shared env, DZ - 1/2 genes+shared env
5
Q
What have behavioural gene studies contributed to psychology?
A
- Relative contributions of genetic and env influence to variation in a trait
- Evidence shows all psych traits show some genetic influence BUT magnitude differs according to trait and age
- Allows to disentangle inter-relationships between two kinds of influence
6
Q
What is the interface of genetic and non-genetic influences?
A
- Both genes and env are important for development
- Everyone must have both so genes can be expressed over environment and development
- Individuals’ genetic endowment can predispose them to be susceptible to particular env influences (Interaction between genes and env)
- May lead to select and construct certain kinds of environment compatible with their endowment (gene-env correlation)
7
Q
What is gene-environment correlation?
A
- An individual’s genetic endowment may lead them to select and construct certain kinds of environment compatible with their endowment
- Having a genetic endowment making a child naturally good at sport is likely to lead that child into an env which is supportive of sporting performance
- A reciprocal process leads to magnification of the behaviour over time = individuals enjoy several env advantages because of their initial higher ability = same for env disadvantages because of genetic endowment = positive feedback loop
8
Q
What are the three types of gene-env correlation?
A
- Passive: parents normally provide genes and env for offspring
- Genes and env are inevitably correlated
- Evocative: an individual elicits certain reactions from others according to genotype
- Active: individual seeks out or creates certain env that are related to genotype (genetic tendency) e.g niche picking
9
Q
What are parental characteristics and env? (Examples)
A
- Heritable characteristics: parenting, psychopathology, smoking in pregnancy, gestational stress
- Child env and genotype therefore correlated: env factor may be marker of genetic vulnerability
10
Q
What is evocative gene-env correlation?
A
- An Individual elicit certain reactions from others according to genotype e.g. smiley babies get more attention than passive babies so this will be strengthened, but aggressive boys evoke hostile reactions from strangers.
11
Q
What is adoption study methodology?
A
- Compare degree of similarity of child to their adoptive parent and bio parent
- If child is more similar to bio parent, genes play role, more like adoptive = env plays a role
- Children are adopted at conception: where parents do not share genetic material with their offspring: rely on studies where offspring adopted at birth
11
Q
What was a study looking at evocative gene-env correlation through adoption studies?
A
- Biological parent’s psych history was made available: antisocial personality disorder and alcohol and drug dependency
- Assessed family env, parenting and child adjustment
- 45 adoptees aged 12-18
- 13 had bio parents with 2+psych disorders, 15 with 1 psych disorder, and 17 with nothing
- Adoptees whose bio parents had a psych disorder were defined as genetically at risk
- Adoptive parents displayed more harsh and inconsistent parenting behaviour and less warmth toward adolescents who’s bio parents had disorders = child evoking negative parenting as a result of their genetic endowment
- Evocative g-e-env involved the greater hostile behaviour that these adoptees exhibited towards their adoptive parenting
11
Q
What are the mutual influences? (Support for evocative)
A
- Findings for father and mother separated
- Psych disorder is predictive of how child is behaving (even when not in same env) = predicts father’s disciplinary practises
- Fathers disciplinary did not change adoptees hostile behaviours
- For mothers: more hostile behaviour = mothers discplinary is affected but this changes hostile behaviours
- Child driven effects in parent-child relationship via gene endowment and behaviour = evidence for evocative correlation
- Mutual process with bidirectional control
11
Q
What is the value of g*e research?
A
- Studies of interaction make it easier to identify novel genetic or non-genetic risk factors for disease
- Can increase understanding about disease mechanisms
- May aid identification of high-risk groups that benefit from targeted interventions
11
Q
What was the mutual influences of parenting (Study 2)
A
- Colorado Adoption Project assessed child adjustment and parenting on 5 occasions between 7-12yo
- Child behaviour at 7yo affected parenting at 12yo but also parenting at 7yo affected child behaviour at 12yo
- More evidence of longitudinal evocative gene-env correlation
11
Q
What was wrong with these studies?
A
- Not completely explained effects on evidence for the role of env mediation (parental control on children)
- Child effects on parenting may be partly explained by env effects = cannot rule out role of env risk
11
Q
What is gene-env interaction?
A
- Individuals’ genetic endowment may predispose them to be susceptible to particular kinds of env influences
- Gene influence on individual susceptibility to particular env
- Can investigate by estimating contribution of genes and env on behaviour
- Context can influence the relative contributions of genes and env
12
Q
What is the first example? (Depression)
A
- Longitudinal study of 883 twin pairs aged 11-18 years
- Family conflict and depressive symptoms assessed
- Estimated the genetic and environmental contribution to individual differences in depressive symptoms
- Allowed the estimates to vary by family conflict
- Stronger effect of family conflict on adolescent depression in individuals at greater genetic risk
- Children with family history of depression may be more vulnerable to family conflict
13
Q
What was the second example? (MAOA)
A
- Parental maltreatment of children
- Studies group of males from birth to adulthood
- Maltreatment in children whose genotype conferred low levels of MAOA expressions more often developed antisocial behaviour and adult violent crime than children with high activity MAOA genotype
14
Q
What is the third example?
A
- Physical maltreatment - increase in risk of violent and ASB in adulthood and adolescence
- Genetic origins: parents provide genotype and rearing env - maltreatment may form a profile of genetically influences ASB
- Mothers’ reports of child maltreatment and childrens’ ASB at age 5 and 7yo
- Found that children who were definitely abused had highest antisocial behaviours at 5 and 7yo, whereas those who had not been abused had negative antisocial behaviours
15
Q
What was the dose-response relationship between likelihood of physical maltreatment and ASB?
A
- Those who had been maltreated had significantly higher levels of later antisocial behaviour.
- Higher scores on ASB after controlling for initial levels of antisocial behaviour = maltreatment independently predicted an increase in adjustment problems.
- Although partly accounted for by genetic effects underlying the relationship, there remained evidence for environmental mediation. Physical maltreatment can be regarded as a risk factor for ASB.
- Environmental effects = potential exists to successfully intervene to reduce the risk of ASB and criminality in children exposed to neglectful parenting and physical maltreatment.
- Interventions that are implemented in the early years of development should be identified and, if effective, used.
16
Q
What is the MZ twin approach?
A
- MZ twins share all genes
- Where differences are found between MZ twins who are reared together, this is estimated as non-shared env influence
- Regression approach to test for env mediation uses env difference score in MZ twins to predict a phenotypic difference score
17
Q
What was a study looking at MZ twins?
A
- Maternal expressed emotion and child ASB
- 565 5yo MZ twins studies longitudinally
- MZ co-twin exposed to more maternal negativity had more antisocial behaviour at age 7
18
Q
What is the value of MZ studies?
A
- Helps understand why there are individual differences in long term effects of abuse and neglect in childhood on adult outcomes
- Research moves us away from reliance on partitioning variance based on MZ vs DZ twins towards increasing specificity of genetics and env influence
19
What is animal research about this?
- Cross-fostering experiments with rhesus monkeys with evidence of interaction effects
- Monkeys carrying short allele of the 5-hTT gene were reactive, aggressive and high alcohol consumption as they grew up
- Only occurs if reared with peers only
- If raised with mother= showed species-normative behaviour
- Has implications for our understanding of individual differences in stress response and adjustment
20
What are pre-natal effects?
- Increased interest in pre-natal factors
- Low birth weight, prematurity
- Maternal stress/anxiety in pregnancy
- Maternal smoking in pregnancy
- Difficult to tell whether associations are causal or markers of genetic propensity
21
What was a study looking at cross-fostering in humans? (Smoking)
- Mothers are either genetically related or unrelated to their children because of assisted reproductive technologies
- IVF study: pre-natal influences and inter-generational transmission factors = allows you to disentangle inherited and env contributions to childhood depression
- In IVF: there are parental gametes as well donated gametes which creates environmental relatives and genetic relatives
- Families who had a birth between 1994 and 2002, successful ART treatment using parents' gametes, sperm donation, egg donation, embryo donation and gestational surrogacy were recruited
- Parental smoking reduced offspring birth weight in related and unrelated groups = prenatal smoking and offspring antisocial behaviour only present for related group
- Prenatal mechanism operated independent of the relationship between maternal and offspring genes
- Consistent with heritable factors accounting for relationship
- For ADHD symptoms, magnitude of associations was higher in the related pairs than unrelated pairs than the unrelated pairs = heritable
22
What was a study looking at effects of maltreatment on antisocial children?
- Study looked at if maltreatment causes antisocial behaviour or if genetics plays a role
- Used a twin sample aged 5 and 7 (same study mentioned before)
- Longitudinal studies showing maltreatment predicts later violence
- G*E shows MAOA gene moderates maltreatment effects
- Maltreatment predicts outcomes over 12 years
- Nurse visitation reduced maltreatment
- More severe maltreatment linked to worse behaviour and these kids showed new antisocial behaviour over time
- Twin analysis showed little genetic influence on maltreatment exposure
- Genetics explained 2/3 variation in antisocial behaviour = parental antisocial history partially explained child outcomes but maltreatment had an independent effect
