The Nature-Nurture Debate

What is the nature-nurture debate concerned with?

The extent to which aspects of behaviour are a product of inherited or acquired characteristics.

Why is nature-nurture not really a ‘debate’?

Any behaviour/characteristic arises from a combination of both.

What is an example of nature and nurture interacting in research?

Bowlby claimed that a baby’s attachment type is determined by the warmth and continuity of parental love (nurture). It was also proposed that a baby’s innate personality (nature) also affects the attachment relationship.

What does the diathesis-stress model suggest?

That behaviour is caused by a biological or environmental vulnerability (diathesis) which is only expressed when coupled with a biological or environmental ‘trigger‘ (stressor).

What does epigenetics refer to?

A change in our genetic activity without changing the genes themselves. It is a process that happens throughout life and is caused by interaction with the environment.

What do aspects of our lifestyle, like smoking or events, like war, we encounter do?

They leave ‘marks‘ on outr, DNA, which switches genes on or off. This explains why factors like smoking have a lifelong influence even after you actually stop - they have changed the way your genes will be expressed.

What may epigenetic changes go on to do?

Influence the genetic codes of our children, as well as their children, and therefore introduces a third element into the debate - the life experience of previous generations.

What does nature refer to?

Inherited influences, or heredity. Early nativists argued that all human characteristics, and even some aspects of knowledge, are innate.

What does nurture refer to?

The influence of experience and the environment.

What do empiricists like Locke argue about the mind?

That it is a ‘blank slate‘ at birth.

What did Lerner identify?

Different levels of the environment: this includes prenatal factors, such as how physical or psychological influences affect a foetus. More generally, development is influenced postnatally in terms of the social conditions a child grows up in, for example.

What can the degree to which two people are similar on a particular trait be represented by?

A correlation coefficient - concordance.

What can concordance provide an estimate about?

The extent to which a trait is inherited - called heritability.

What is heritability?

The proportion of differences between individuals in a population, with regards to a particular trait, that is due to genetic variation.

A figure of 1% means genes contribute almost nothing to individual differences and 100% means genes are the only reason for individual differences.

What does the general figure for heritability in IQ being around .5 mean?

That about half of a person’s intelligence is determined by genetic factors and the other half must be environmental.

What are the strengths of research into the nature-nurture debate?

• Adoption studies.

• Epigenetics.

• Real-world application

How are adoption studies a strength of research into the nature-nurture debate?

Adoption studies are useful because they separate the competing influences of nature and nurture. If adopted children are found to be more similar to their adoptive parents, this suggests the environment is the bigger influence. Whereas, if adopted children are more similar to their biological parents (no influence on their environment), then genetic factors are presumed to dominate. A meta-analysis of adoption studies by Rhee and Waldman found that genetic influences accounted for 41% of the variance in aggression.

What do adoption studies show?

How research can separate the influences of nature and nurture.

What is the counterpoint to the adoption studies?

Research suggests that this approach may be misguided, that nature and nurture are not two entities that can simply be pulled apart. According to Plomin, people create their own 'nurture by actively selecting environments that are appropriate for their nature. Thus, a naturally aggressive child is likely to feel more comfortable with children who show similar behaviours and will choose their environment accordingly. Then, their chosen companions further influence their development. Plomin refers to this as niche-picking.

What does the counterpoint to the adoption studies suggest?

This suggests that it does not make sense to look at evidence of either nature or nurture.

How are epigenetics a further strength of the debate?

One example of how environmental effects can span generations presumably through epigenetic effects comes from events of the Second World War. In 1944, the Nazis blocked the distribution of food to the Dutch people and 22,000 died of starvation, in what became called the Dutch Hunger Winter. Susser and Lin report that women who became pregnant during the famine went on to have low birth weight babies. Whilst this may be unsurprising, what is more interesting is that these babies were twice as likely to develop schizophrenia when they grew up compared to more typical population rates.

What do epigenetics support?

The view that the life experiences of previous generations can leave epigenetic 'markers' that influence the health of their offspring.

How is real-world application a strength of the debate?

Research suggests that OCD is a highly heritable mental disorder. For example Nestadt et al. put the heritability rate at .76. Such understanding can inform genetic counselling because it is important to understand that high heritability does not mean it is inevitable that the individual will go on to develop the disorder. This means that people who have a high genetic risk of OCD because of their family background can receive advice about the likelihood of developing the disorder and how they might prevent this (e.g. learn to manage stress).

What does the real-world application show?

That the debate is not just a theoretical one but that it is important, at a practical level, to understand the interaction between nature and nurture.