Genetic explanations of autism (biological)

AQA b, unit 2 exam

Individual differences: autism

Biological explanation: genetic

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Genetic explanations of autism (biological)

Advantages

  • Bolton (1994) found that there was an approximately 3% concordance in siblings.
  • Folstein and Piven (1991) also found a 3% concordance rate between siblings. Approximately 4:1 as autism is more prevalent in boys than girls.
  • Folstein and Piven (1991) also found a 96% concordance rate for monozygotic twins.
  • Rivito (1985) studied 23 sets of identical and 17 sets of non-identical twins. There was a 96% concordance rate with monozygotic twins and a 23% concordance rate with dizygotic twins.
  • Bee (1989) found 10% of autistic children have chromosomal abnormalities known as the fragile X syndrome.

Disadvantages

  • No one study has ever found a 100% concordance rate therefore if autism was purely genetic then this figure should have been found. As a result, nurture must play a part in autism.
  • Twin studies are rare and so the sample size is small, this means you can't make generalisations.
  • There is a high dropout rate with twin studies.
  • Monozygotic twins are usually reared in the same environment. Therefore the high concordance rate might be due to nurture rather than nature.
  • With the autistic gene, the results are inconclusive and research is ongoing. If it is truly found then this could lead to unethical mass screening and termination.
  • The gender abnormalities may be linked to Tourettes and OCD (as well as autism) as Comings and Comings (1991) said that these three disorders are similar. E.g. they all want to stick to a routine.

Evaluation

Cason et al (2000) concluded that if autism was entirely caused by genetics then identical twins would have 100% concordance which suggests that autism is influenced by the environment; nurture. 

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