Behavioural Genetics

Question 1

Define heritability

Answer 1

Proportion of the total variation in the population that’s due to genetic variation

H^2=VG/VP
(genetic/phenotypic variance)

Question 2

Give examples of human behaviour with genetic components

Answer 2

• Huntington’s- higher number of CAG repeats

• Alzheimer’s- associated with plaque build up in brain. Locus on ch21- Apolipoprotein E. E2,E3,E4 alleles. Homozygous E4 have earlier age of incidence. Also have poorer outcomes from traumatic brain injury
(Houlden & Greenwood, 2006)
(and enhances HIV cell attack and accelerates disease progression
(Burt et al., 2008))

Mental illness- schizophrenia, anxiety, alcoholism, bipolar disorder
• Incidence increases with relatedness

Autism
• Repetitive behaviour, poor social behaviour and language skills
• Deletions across at many loci across genome are associated with it

Question 3

Give examples of animal behaviour with genetic components

Answer 3

Dogs
• Narcolepsy in dachshunds- one locus
• Basset Hounds prone to paranoia- gene involved is same as that of human schizophrenia
• Pit bulls- bite and hold
• Pyrenean mountain dog- neotenous, friendly, unintelligent

Wild silver fox- Dmitry Belyaev
• Bred tamest, after 15 generations domesticated foxes produced
• Formed white spots and wagged tails like dogs
• Gene involved causes lower adrenaline activity and affects melanin production

Question 4

Outline the genetics of IQ

Answer 4

• Clear genetic component shown with twin studies
• Environmental factors also play a part- Flynn effect- IQ increased with time
• Heritability of IQ increases with age
• Heritability increases with income
-> influence of genes depends on environment