genetic explanation Flashcards
what is the genetic explanation?
SZ tends to run in families
- while a person may inherit a vulnerability to SZ they may not develop the same form
twin and sibling studies provide reliable evidence for the genetic explanation
what is a strength of the genetic explanation?
there is evidence supporting this explanation
- tienari identified adopted offspring of biological mothers who had been diagnosed with SZ(n=112). he compared this group with adopted offspring of mothers who had not been diagnosed with any mental disorder (n=135)
- the results showed that 7% of the group who had mothers with SZ compared to only 1.5% of the controls.
what is the competing argument of the strength?
genetics is not all there is to it as in MZ twins the concordance rate in only 40-50%
- these twins are 100% identical so we would expect the concordance rate to be 100% if genetics was the only factor
what evidence is there supporting the view that genetics are not the only factor?
gottesman found that in DZ twins the concordance rate was 17% while in MZ tins it is 48%.
- both sets share prenatal and post-birth environments, but MZ twins share 100% while DZ only 50%
gottesman also found that regular siblings only had 9% concordance rate
what is a weakness of the genetic explanation?
family and twin research fails to control for environmental influences.
- but adoption studies remove this problem because tey examine concordance of children that have been separated from their biological parents
what is the nature nurture weakness?
biological explanations of SZ ignore the role of external influences on the development
- social factors have been implicated in explanations for SZ
- research has found that SZ is more common in deprived areas (maybe increased drug use)
what is the diathesis stress model?
SZ develops in those who have a biological disposisition to developing the illness due to genetic, neurochenical or neuroanatomic factors but who also have some kind of environmental trigger.
