Genetics and Parenting - ADHD Nature or Nuture?
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ADHD is a label applied to children exhibiting a broad range of inattentive and/or hyperactive behaviours, to a degree that is considered "dysfunctional". It is obvious that childhood behaviour patterns are influenced by both nature and nurture. Genetics has key a role in determining personality and dysfuntional parenting can cause dysfunctional behaviour in their children.
ADHD proponents however, caution against blaming parents. They exempt parents from responsibility for their child's behaviour by assuring them "it is not their fault". Instead they attribute problematic ADHD type behaviour solely to genetics, and assert it is highly likely that one or both parents will also have ADHD.
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Despite these assertions no specific genes, or combination of genes, have been identified. The failure to identify specific genes is not caused by a lack of looking. Considerable research effort has been expended searching for the hypothesised genetic basis of ADHD. There have been several false dawns, where hyped claims that the genes that cause ADHD have been identified, have on closer inspection, been shown to be false (e.g. see the case study below).
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Finding a genetic basis for ADHD would involve finding a genetic basis for inattentive and/or impulsive/hyperactive behaviour. It is obvious that individual behavioural differences, like distractibility and hyperactivity, are in part determined by genetics, and twin and family studies have suggested a strong genetic component in ADHD type behaviours.[1][2] However, even if researchers found consistent genetic or other biological diagnostic differences between people who consistently display ADHD-like behaviours and those who don’t, that would not make ADHD a legitimate psychiatric disorder.
As Queensland psychologist Bob Jacobs points out difference is not disease:
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Case study - Hyped claims of proof of genetic basis of ADHD don't stand scrutiny.
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In September 2010 the world media buzzed with the news that British researchers had found the ‘Holy Grail’ for proponents of ADHD, by proving its genetic basis.[4][5][6] The psychiatrist who jointly led the much hyped research, Professor Anita Thapar of Cardiff University, emphatically proclaimed ‘now we can say with confidence that ADHD is a genetic disease’.[7] In reality the research did not support Professor Thapar’s ambitious assertion. However, by the time critics had identified the flaws in Professor Thapar’s claim, the media circus had moved on and millions of people around the globe had read, seen or heard the unchallenged proclamation that ADHD is a ‘genetic disease’.
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Professor Thapar’s research is typical of the flawed science that supports the widespread drugging of children with amphetamines to control their inattentive, hyperactive and, many would say, ‘childish’ behavior. The study involved comparing the genetic codes of 366 children ‘with ADHD’ with that of 1047 ‘non-ADHD’ control children.[8] Thapar’s group found 13.9 percent (51) of children with ADHD had short lengths of their genetic code that were either duplicated or missing. This compared with 7.4 percent (78) of the ‘control children’ (Williams et al, 2010). In other words, the vast majority of ‘ADHD children’ (86 percent) did not have the hypothesised ‘ADHD genes’ and some ‘non-ADHD children’ did.
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Even the 13.9 percent to 7.4 percent difference is of questionable significance as there appears to be significant differences between the average IQ of the two groups. The mean recorded IQ of the 366 children ‘with ADHD’ was 86, fourteen points below the general population average of 100. Whilst the IQ of the 1047 ‘non ADHD’ children was not specified, presumably they were as intelligent as the general population (average IQ of 100). Furthermore, when 33 intellectually impaired ‘ADHD children (IQ lower than 70) were excluded from the ADHD cohort only 11% of the remaining 333 had the hypothesised ADHD genetic abnormality. Even with the intellectually impaired children removed, the average IQ (89) of the 333 remaining in the ADHD group was significantly lower than the control group (presumed to be 100).[8]
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To be a valid comparison the study should have compared like with like. That is, the ‘ADHD’ cohort of children should have had the same average IQ as the ‘non-ADHD’ cohort of children. However the reason offered by the authors for not comparing like with like was convenience not science; being that they did not have IQ measures for the control group. The authors offered the explanation that the low average IQ of the ADHD cohort was of no consequence as the non-ADHD cohort included ‘individuals spanning a wide IQ spectrum which presumably includes those with a lower IQ’.[8]
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This evidence is more suggestive of a relationship between the identified genetic abnormality and intellectual disadvantage than it is of ADHD. The authors of the study acknowledged the likely association between intellectual disability and the genetic abnormality identified but defended their comparisons of populations with a low average IQ (89) with a normal control population. Whilst there is considerable anecdotal evidence of bright but under-stimulated and bored children being diagnosed with ADHD it could be for the geographical population of this study that having a low IQ increases a child’s chances of being diagnosed with ADHD. All of this, of course, was lost on the media. They reported Thapar’s overblown, unsubstantiated conclusion as scientific fact and failed to report the IQ differences between so called ‘ADHD children’ and normal children.
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References
[1] Chapter 2 of Retz W, Klein RG (eds): Attention-Deficit Hyperactivity Disorder (ADHD) in Adults. Key Issues in Mental Health. Basel, Karger, 2010, vol 176, pp 38–57 Family and Twin Studies in Attention-Deficit Hyperactivity Disorder Christine Margarete Freitaga Wolfgang Retzb https://pdfs.semanticscholar.org/9aa3/a2cd8cad40e4609ec0809098f4800907716a.pdf?_ga=2.193908457.596256221.1554642568-330357463.1552517179
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[2] Larsson, H., Chang, Z., D’Onofrio, B. M., & Lichtenstein, P. (2013). The heritability of clinically diagnosed attention deficit hyperactivity disorder across the lifespan. Psychological Medicine, 44(10), 2223–2229. https://www.ncbi.nlm.nih.gov/pubmed/24107258
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[3] Bob Jacobs, Youth Affairs Network of Queensland, Being an Educated Consumer of ‘ADHD’ Research, Youth Affairs Network of Queensland, 2005 http://www.atca.com.au/wp-content/uploads/2012/09/Bob-Jacobs-being-an-educated-consumer-of-ADHD-research.pdf
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[4] Kelland, K. (2010) Study finds first evidence that ADHD is genetic,Reuters, 30 September 2010. Available at http://www.reuters.com/article/2010/09/30/us-adhd-genes-idUSTRE68S5UD20100930 (accessed 22 November 2012);
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[5] Landau, E. (2010) ADHD is a genetic condition, study says, CNN Health, 29 September 2010. Available at http://thechart.blogs.cnn.com/2010/09/29/adhd-is-a-genetic-condition-study-says/ (accessed 14 November 2012)
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[6] ABC Online News Study finds genetic link to ADHD, 30 September 2010. Available at http://www.abc.net.au/news/2010-09-30/study-finds-genetic-link-to-adhd/2280292 (accessed 22 November 2012)
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[7] ABC Online News Study finds genetic link to ADHD, 30 September 2010. Available at http://www.abc.net.au/news/2010-09-30/study-finds-genetic-link-to-adhd/2280292 (accessed 22 November 2012)
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[8] Williams N, Thapar A, et al. Rare chromosomal deletions and duplications in attention-deficit hyperactivity disorder: a genome-wide analysis, The Lancet. Volume 376, Issue 9750, 23–29 October 2010, Pages 1401-1408. Available at https://www.sciencedirect.com/science/article/pii/S0140673610611099#! (accessed 31 March 2019)
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