Nature and nurture interplay: family and genetic influences

what are the types of gene-environment interplay?

• epigenetics (e → g)

• gene-environment correlation (g → e)

• gene-environment interaction (g x e)

what is vertical genetic transfer?

the way that genetic material (DNA) is passed on from parents to offspring

what is the human genome made of?

3 billon nucleotide base pairs

how many genes are in the human genome?

20-25,000

how much of the DNA sequence is variable ?

approx. 1%

what is gene expression?

process by which the DNA sequence of a gene is converted into functional protein structures

what is DNA methylation?

methyl groups attach to DNA compacting it and preventing its code form being read or made into proteins

what do genetics do?

determines what specific proteins are synthesised

what do epigenetics do?

determines how much of the proteins is made, and where and when it is synthesised

how does nurturing behaviour affect offspring?

• high-nurturing mothers raise low anxious offspring

• low-nurturing mothers raise high anxious offspring

how does nurturing behaviour in mother rats affect their children?

• affects epigenomes - in offspring with a low-nurturing mother, the glucocorticoid receptor gene (Ne3c1) is switched off and leads to higher levels of stress and anxiety

• the epigenetic pattern that the mother establishes tends to stay even after the pups become adults

what affects epigenetic modulation?

examples include:

• diet

• psychological state

• social interactions

• exercise

what is gene-environment correlation (rGE)?

when individuals with a genetic propensity for a trait are in environment, they choose or create the environments that support expression of the trait

what are the types of gene-environment correlation?

• passive

• evocative

• active

what is passive gene-environment correlation?

parental genes influence parental behaviours that play a role in determining the kind of rearing environment that they provide

what is evocative gene-environment correlation?

child genes influence child behaviours that play a role in evoking different types of responses in other people

what is active gene-environment correlation?

child genes influence child behaviours that play a role in determining how children shape and select their environments

what is the source of passive gene-environment correlation?

parents and siblings

what is the source of evocative gene-environment correlation?

anybody

what is the source of active gene-environment correlation?

anybody or anything

how does the importance of the types of rGE effects change with development?

• the influence of passive rGE declines from infancy to adolescence

• the importance of active rGE increases from infancy to adolescence

what mechanisms could be causing the increase of the degree to which experience is influenced by an individual’s genetic factors?

• genetic innovation (new genes become important)

• genetic amplification (individuals select their own experiences)

what is gene-environment interaction (GxE)?

• genetically influenced sensitivity to specific environment

• genetic influences on a trait depend on the environment

  • specific environments and genetic susceptibilities to these environments predict a trait

what are the models for GxE?

• diathesis-stress/dual risk model

• differential susceptibility model