The Nature-Nurture Debate

The Nature-Nurture Debate: Concerned with the extent to which aspects of behaviour are a product of inherited or acquired characteristics

Interactionist Approach: A way to explain the development of behaviour in terms of a range of factors, including both biological and psychological ones. Most importantly such factors don’t simply add together but combine in a way that can’t be predicted by each one separately.

Diathesis-Stress Model: Suggests behaviour is caused by a biological or environmental vulnerability which is only expressed when coupled with a biological or environmental “trigger”. For example, the genetic vulnerability of OCD doesn't always lead to OCD but there’s a higher chance if the patient suffered trauma.

Epigenetics: Refers to a change in our genetic activity without changing the genes themselves through interaction with the environment, such as trauma, smoking or dieting and their mark on DNA.

Nature: Refers to inherited influences (heredity). Descartes argued all human characteristics are innate, including intelligence or personality.

Nurture: Refers to the influence of experience and the environment. Empiricists, such as Locke, argued the mind is a blank slate at birth which is then shaped by the environment. Lerner identified the levels of environment, including prenatal and postnatal factors.

Measuring Nature and Nurture: Concordance provides an estimate of the extent to which a trait is inherited (heritability), which is the proportion of differences between individuals in a population, with regard to a particular trait, that is due to genetic variation. A figure of 0.01 means genes contribute almost nothing to individual differences and 0.1 means genes are the only reason for individual differences. IQ has a heritability of about 0.5.

Adoption Studies: Adoption studies separate the competing influences of nature and nurture as if adopted children are found to be similar to their adoptive parents, this suggests the environment is the bigger influence and vice versa if they’re the same for biological similarity. Rhee and Waldman (2002) conducted a meta-analysis of adoption studies and found that genetic influences accounted for 41% of the variance in aggression.

Counterpoint to Adoption Studies (Nature v. Nurture): Robert Plomin (1994) suggested people create their own “nurture” by actively selecting environments that are appropriate for their “nature” and so a naturally aggressive child is likely to feel more comfortable with children who show similar behaviours and will ‘choos’ their environment accordingly. Plomin called this niche-picking.

Epigenetic Strengths: Susser and Lin (1992) reported that women who became pregnant during the Dutch Hunger Winter went on to have low birth weight babies and these children were twice as likely to develop schizophrenia when they grew up compared to more typical population rates.

Real-World Applications (Nature v. Nurture): Nestadt et al. (2010) put the heritability rate of OCD at 0.76. This can inform genetic counselling as it is important to understand that high heritability doesn’t mean its inevitable. This means those with a high genetic risk of OCD can receive advice about the likelihood of developing the disorder and how they might prevent this.