one adoption study

Question 1

what are adoption studies?

Answer 1

Compare the concordance rate of an adoptee with their biological and adoptive parents.

Question 2

what does it suggest if concordance rate is higher in adoptive relatives than biological?

Answer 2

environmental cause

Question 3

tienari

Answer 3

Adopted children from families with schizophrenia (SZ) were compared to adopted children from families without SZ

• Those with family history of SZ had more chance of developing the illness (9.4% lifetime risk) than children from families with no history of SZ (1.2% lifetime risk).

This supports a genetic link.

• However, those children from families with SZ were less likely to develop the illness if placed in a “good” family with kind relationships, empathy, security, etc.

So environment does play a part in triggering the illness.

Question 4

strength of adoption studies - control

Answer 4

P: Adoption studies control the influence of environment so differences between sets of adoptees can be said to be genetic.

E: Tienari found adoptees whose mother’s had SZ had a higher lifetime risk of developing SZ (9.4%) than compared to adoptees whose mothers did not have SZ (1.2%).

Therefore the influence of nature vs nurture can be measured.

Question 5

strength of adoption studies - env plays a role

Answer 5

P: Useful to show the environment may play a greater role than twin studies suggest

E: Tienari found children from families with SZ were less likely to develop the illness if placed in a “good” family with kind relationships, empathy, security, etc. So the environment does play a part in triggering the illness.

T: Thus adoption studies should be used in addition to twin studies to ensure overestimations aren’t made.

Question 6

weaknesses of adoption studies - lack validity

Answer 6

P: Adoptive studies may lack validity because of ‘selective placement’.

E: The adoptive children in Tienari’s study may have adoptive families similar to their biological ones.

T: Therefore some of the similarities with biological relatives is actually due to environmental similarities rather than genes.

Question 7

weaknesses of adoption studies - generalisability

Answer 7

P: Adoption studies have limited generalisability.

E: Parents in Tienari’s study were likely to be better educated, low rates of mental health issues and have high income.

T: Therefore conclusions about the effects of genes on SZ may not be generalisable to the population as a whole.