Genetic basis of sz

The genetic explanation of sz suggests that sz is passed down from one generation to another through genes. It’s the idea some people are born with a gene or multiple genes (candidate genes) that make them predisposed to the symptoms.

Individual genes are thought to cause sz however it’s widely believed that sz is polygenic, where multiple gens must be present to develop the disorder. Ripke carried out a large study and found that 108 different genetic variations were associated with sz.

It has also even noted that sz runs in families. Gottesman found that as genetic similarity ncreases so does chance of developing sz. win studies found identical twins have a 48% shared risk whereas DZ twins have a 17% risk.

Through adoption studies Heston also ound that 16% of adopted children whose mothers had sz and got adopted at days old also had the condition which is well above 1% normal chance level showing there is a genetic predisposition is the development of Sz.

Evaluation

Family studies tend to provide weak evidence as families tend to share same environment. Acts as a confounding variable as we don’t know if we are measuring genes or environment which owners internal validity of findings meaning role of nurture cant be eliminated.

There is evidence that sz isnt wholly genetic. Gottesman finings were 48% but if they share 100% of dna and it was purely biological then the concordance rates should be 100%. his isn’t a full explanation of sz.

Concordance rates in old studies are less reliable due to changes in diagnostic criteria. Now I’d go is is much more rigorous than it originally was meaning some research lacks external validity.

However adoption studies show that identical twins still have a higher risk of developing sz. Therefore this shows nature not nurture supporting genetic explanation for sz.