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Individual differences and Crime > Behavioural genetics > Flashcards

Behavioural genetics Flashcards

1
Q

What is evolution?

A
  • Individuals are similar but not identical
  • Characteristics passed from parent to offspring
  • Not all individuals survive to pass on their genes
  • Characteristics that confer survival and mating advantage will survive into future generations and become more common
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2
Q

Genes

A
  • Set of instructions for running the body
  • Reside on strands of DNA
  • RNA enters nucleus of the cell to
    pick up the instructions from the gene
    (transcription)
  • Returns to the rest of the cell where it gathers a
    specific group of amino acids that form
    a particular protein (translation)
  • Proteins are the building blocks of life
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3
Q

Genotypes

A
  • Transmitted across generations
  • Explains why people canbe a carrier for a gene
  • Changes to the phenotype during individual’s lifetime are not passed on to offspring
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4
Q

Phenotype

A
  • Biological/physical/behavioural/psychological trait caused by an individual’s genotype
  • Majority of cells in body contribute to maintaining phenotype (e.g.,liver cells)
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5
Q

Gamets

A
  • Few cells concerned with making more genotypes (eggs in females and sperm in males)
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6
Q

Chromosomes

A
  • Tightly wound lengths of DNA
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7
Q

How does variation emerge?: Recombination

A
  • DNA exchanged between paired chromosomes in stage before meiosis (gamate formation)
  • Happens every time gamete is formed
  • Increases variation even further
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8
Q

How does variation emerge?: Linkage

A
  • Genes that reside in close proximity on the strand of DNA tend to be inherited together (travel together)
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9
Q

How does variation emerge?: Mutation

A
  • Segmental duplications
  • Chunks of DNA make an extra copy of itself during replication so now extra genes that are also subject to mutations that lead to some new function
  • Gene families – multiple genes descended from a common ancestor by duplication events
  • If this leads to some phenotype that confers survival or mating advantage, then natural selection will retain that trait within the population
  • Vast majority of mutations either don’t lead to any type of phenotypic effect, or are detrimental to the individual
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10
Q

Alleles

A
  • Different versions of the same gene
  • Dominant or recessive
  • Single gene charcteristics- where allele causes one phenotype (eg; traits like red hair)
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11
Q

Genes and behaviour

A
  • Link between genes and behaviour is changes in neuronal or hormonal mechanisms
  • Behaviour as a phenotype
  • Monoamine oxidase- enzyme from the MAOA gene located on the chromosome – helps regulate serotonin
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12
Q

Genes and behaviour: Burner et al (1993)

A
  • Study of dutch extended family
  • Number of male relatives had severe conduct disorder (violence, rape and arson)
  • Men found to have absence of MAOA activity
  • MAOA was sequenced and found gene no longer coded correctly for amino acids
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13
Q

Quantitative genetics

A
  • Estimates extent observed differences among individuals are due to genetic differences and environmental differences without specifying what those factors are
  • Produces “heritability estimate”
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14
Q

Heritability

A
  • Proportion of pheotypic variance that can account for by genetic differences in individuals
  • Does not refer to genetic contribution to a trait
  • Estimated from correlations between blood relatives
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15
Q

How to estimate heritability: Adoptive designs

A
  • Genetic and environmental causation of behaviour estimated by looking at behavioural similarities and differences between genetically related individuals growing up in different environments
  • Early research showed on average, genetics contribute (around 50%) to personality traits
  • Schizophrenia (Heston, 1966)- found children of Schizophrenic parents just as likely to develop schizophrenia irrespective of whether they grow up with their birth or adoptive parents
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16
Q

How to estimate heritability: Twin designs

A
  • Comparison of monozygotic (genetically identical) and dizygotic twins (same relatedness as siblings)
  • Monozygotic twins should be phenotypically more similar than dizygotic twins
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17
Q

Interpreting heritability

A
  • Both genetic and environmental influences contribute to educational attainment
  • When child experience differences in quality of education and upbringing, then heritability is reduced because of the greater contribution from environmental influences
  • Heritability describes what is in a population at a particular time
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18
Q

Shared environmental influences

A
  • Non-genetic influences that make family members similar to each other
  • Appear to contribute little to personality traits and cognitive abilities
  • Family resemblance that is not explained by genetics
  • Resemblance amongst adoptive relatives
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19
Q

Non-shared environmental influence

A
  • Non-genetic influences that are independent for family members
  • Your individual experience growing up that is unique to you
  • Anything that is left after removing the genetic and shared-environmental influence
  • Twin studies – birth weight, parental negativity -> behaviour problems and academic achievement, but also mediated by genes
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20
Q

How genetics shape environment

A
  • Shared positive affect & responsiveness in 3-year-olds and their parents (Deater-Deckard & O’Connor, 2000)
  • Family relations such as marital quality and parenting (Ganiban et al., 2009)
  • Relationships & control of finances
  • Friends and peer groups
  • Perception of classroom environment (Walker & Plomin, 2006)
  • Television (Plomin et al., 1990)
  • Work environments (Hershberger et al., 1994)
  • Social support (multiple studies)
  • Exposure to drugs (Tsuang et al. 1992)
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21
Q

Types of genotype x environment correlation (Plomin et al., 1977)- Passive

A

Children receive genotypes correlated with their family environment

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22
Q

Types of genotype x environment correlation (Plomin et al., 1977)- Evocative

A

Individuals are reacted to on the basis of their genetic propensities

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23
Q

Types of genotype x environment correlation (Plomin et al., 1977)- Active

A

Individuals seek or create environments correlated with their genetic proclivities

24
Q

Gene x environment interaction

A
  • Genetic sensitivity or susceptibility to environments
  • Effect of environment on a phenotype depends on genotype
  • Effect of the genotype on the phenotype depends on the environment
25
Q

Bohman, 1996; Brennan et al., 1996

A
  • Adoptees whose birth parents have criminal convictions, are at risk of criminal behaviour (genetic)
  • Adoptees whose adoptive parents have criminal convictions are at risk of criminal behaviour (environmental)
  • Criminal convictions of adoptive parents led to increased criminal convictions of their adopted children more so when adoptee’s birth parents also had criminal convictions
26
Q

Leve et al., 2010

A
  • Adopted children whose birth parents had more psychopathology symptoms benefit from adopted mother’s structured interactions at 18 months old
  • Children whose adopted parents who had psychopathology symptoms were at risk for developing behavioural problems- only when birth parents were high in psychopathology
27
Q

Kendler et al., 1995

A

Effect of stressful life events on depression are worse for individuals at genetic risk for depression

28
Q

Jaffee et al., 2005

A

Effect of physical maltreatment on conduct problems is greater for children at genetic risk for conduct problems

29
Q

Hanscombe et al., 2012

A

Socioeconomic status does not moderate the heritability of children’s intelligence

30
Q

Tuvblad et al., 2006

A

High heritability of adolescent antisocial behaviour in economically advantaged families

31
Q

Feinberg et al., 2007

A

High heritability for adolescent antisocial behaviour when parenting is negative

32
Q

MAOA gene (Caspi et al., 2002):

A
  • No difference in behavioural outcome for children with low or high MAOA genotype in the absence of child maltreatment
  • Children with MAOA genotype developed antisocial behaviour when exposed to child maltreatment
33
Q

5-HTTLPR serotonin transporter gene (Caspi et al., 2003):

A
  • No difference in relationship between gene and depressive symptoms in absence of stressful life events
  • Presence of depression significantly higher in presence of gene and an increasing number of stressful life events
34
Q

Schizophrenia

A
  • Delusions, hallucinations, disorganised speech and behaviour, low emotionality, & lack of motivation
  • General population – risk of 1%
  • Second degree relatives – 4%
  • First degree relatives– 9% (For offspring – 13%)
  • Identical twin – 46%
35
Q

Schizophrenia & adoption studies: Heston, 1966

A

Risk of schizophrenia in adopted children whose birth mother is schizophrenic is 11% compared to adoptees whose birth parents do not have schizophrenia (0-1%)

36
Q

Schizophrenia & adoption studies: Tienari et al., 2004

A

10% of adoptees with schizophrenic parents report some form of psychosis (rate of 1% in adoptees without schizophrenic parents)

37
Q

Schizophrenia & adoption studies: Kety et al., 1994)

A

Schizophrenia is not influenced by the home environment fostered by schizophrenic parents

38
Q

Major depressive disorder (MDD) & bipolar disorder (BD): Family studies

A
  • Increased risk for first degree relatives – 9%
  • MTHFR gene variant implicated
  • Early onset, drug use & suicide attempts, response to medication potentially more heritable in BD (Smoller & Finn, 2003; Schulze et al. 2006; grof et al., 2002)
39
Q

Major depressive disorder (MDD) & bipolar disorder (BD): Twin studies

A
  • MDD – 38% (no shared environmental influence; Kendler et al., 2006), but maybe as much as 70% (McGuffin et al., 1996)
  • Concordance rates for MZ /DZ twins – 43%/28%
  • BD – Concordance rates for MZ /DZ twins – 65/7%; 40/5%; 55/7%
40
Q

Autism/ASDs

A
  • Twin studies show high concordance rates for MZ twins far beyond DZ twins (at least 60%)
  • Now considered one of the most heritable conditions (Freitag, 2007; Ronald & Hoekstra, 2011)
  • Genetic influence is the same irrespective of severity
  • 3 impairments of autism: poor social interaction, language & communication problems, and restricted range of interests and activities are influenced by different genes
  • 100 genes are associated
  • Some cases due to rare mutations (only 10%)
41
Q

ADHD

A
  • First degree relatives 5 times more likely to be diagnosed (Biederman et al., 1992)
  • Research consistently demonstrated strong genetic influence for the hyperactivity component, perhaps up to 76% heritability
  • Heritability greater for ADHD which continues into adulthood
  • Substantial genetic overlap for the inattention and hyperactivity components of ADHD
42
Q

Co-occurrence of disorders

A
  • High levels of comorbidity
  • Genetic overlaps between MDD and BD, and BD and schizophrenia
  • Genetic overlap among anxiety disorders – differences caused by non-shared environmental factors
  • Anxiety and depression caused by the same genetic factors (Kendler et al., 1992)
  • Non-shared environmental influences appear to be the differentiating factor (Kendler 1996; Mddeldorp et al., 2005)
43
Q

Genetics research suggests two over-arching categories of disorders: Internalising

A

Anxious/misery
- Major depression/GAD/Panic disorder

Fear:
- Panic disorder/animal phobia/situational phobia

44
Q

Genetics research suggests two over-arching categories of disorders: Externalising

A

Alcohol dependence/other drug abuse or dependence/antisocial behaviour/CD

45
Q

Personality: Loehlin & Nichols (1976)

A
  • Nearly all personality traits show moderate heritability (30 – 50%)
  • Environmental influence not to do with parents but actually non-shared environment
46
Q

Other FFM traits

A
  • Openness to experience – 45%
  • Conscientiousness – 38%
  • Agreeableness – 35%
    (Loehlin, 1992; Jang et al., 1996)
  • Sensation seeking (60%) (Fulker et al., 1980; Koopmans et al., 1995)
47
Q

Other contexts: Situational change

A
  • In a lab task, identical twins changed similarly in adapting to different tasks than non-identical twins (Mateny & Dolan, 1975)
  • Genetic influence in stability of shyness in different situations (Cherny et al., 1994)
  • Personality trait changes across different situations (Dworkin, 1979)
  • Genetic influence in how people respond to personality questionnaires (Eaves & Eysenck, 1976; Hershberger et al., 1995)
48
Q

Other Contexts: Relationships

A

Parent-offspring:
- Attachment – moderate heritability, but substantial shared environmental influence

Romantic
- Quality of relationship (15 – 35%)
- About 50% of relationship quality affected by personality – so indirectly by genetics

49
Q

Other Contexts: Sexual Orientation

A
  • 34-39% for men (+ non-shared environments)
  • 20% for women (+ modest shared environmental influence) (Langstrom et al., 2010
50
Q

Other Contexts: Self esteem

A

Modest genetic influence, but no influence for shared family environment

51
Q

Other Contexts: Attitudes and interests

A

Traditionalism, sexual & religious attitudes – 50% genetic, shared environment – 15%
(Eaves et al., 1989; Olson et al., 2001)

52
Q

Personality disorders

A
  • Different from psychopathology as people affected consider it as part of their personality, rather than a condition
53
Q

Schizotypal PD

A
  • Less intense version of schizophrenia
  • Runs in families
  • 33% concordance rate for MZ twins, and 4% for DZ twins (Torgersen et al., 2000)
  • Risks of schizotypal personality disorder are 11% for first-degree relatives
  • Twin study suggests negative and positive aspects of schizotypy differ genetically (Linney et al., 2003)
  • Schizotypy is genetically related to schizophrenia (Jang et al., 2005)
54
Q

ASPD

A
  • Risk for ASPD increased 5x for first degree relatives of ASPD males

Antisocial behaviour:
- Genetics – 40%; shared environmental influence – 15%; non-shared – 16% (Rhee & Waldman, 2002)

  • Non-shared environment contributes to change as individual gets older (Burt et al., 2010)
  • Increased rate of ASPD in the adopted children of birth parents with criminal records (Cadoret & Stewart, 1991; Crowe, 1974)
55
Q

Criminal behaviour

A
  • Concordance rate: 52% MZ twins; 21% DZ twins
  • Adopted children greater risk for criminal behaviour when birth parents have criminal convictions (Mednick et al., 1984)
  • Appears to be for property crimes not violent
  • G x E interaction – adopted children greater risk if both adopted and birth parents engage in criminal activity (Beaver, 2011)
  • Twin studies might over-emphasise genetic effects – partners in crime
  • Genetic influence contributes to both ASPD and substance use disorders:
  • Adoptees (male & female) increased biological risk for ASPD – increased aggressiveness, CP, ASPD and substance dependence (Cadoret et al., 1995; Cadoret et al., 1996)

Individual differences and Crime (9 decks)

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