Issues & Debates: The Influence Of Nature

Nature is the view that behaviour is the product of innate biological or genetic factors. For a long time, psychologists have known that certain physical characteristics, such as eye colour, skin pigmentation and certain diseases (e.g. Huntingdon’s) are biologically determined and the result of heredity (or genetic inheritance). Heredity is the process in which traits are passed down from one generation to the next. Furthermore, characteristics like height, weight, hair loss, life expectancy and vulnerability to specific illnesses are positively correlated with genetic relatedness. This has led psychologists to investigate whether psychological characteristics are also “wired in” before we are born.

This is known as the nativist position, and the basic assumption is that the characteristics of the human species are a product of evolution and that individual differences are the result of each person’s unique genetic code.

For example, family, twins and adoption studies show that the closer the relatedness of two people, the more likely it is that they will show the same behaviours. For example, the risk of being diagnosed with schizophrenia is approximately 1% of the general population. However, Gottsman and Shields (1991) pooled the results of around 40 family studies and found that the risk increases to 46% for those with two parents who have schizophrenia. Also, Joseph (2004) pooled the data for schizophrenia studies conducted before 2001 and found an average concordance rate of 40.4% for MZ twins and 7.4% for DZ twins, highlighting a significant genetic component.

Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded by nativists as the product of maturation, as we have a “biological clock” which switches certain behaviours ‘on’ or ‘off’ in a pre-programmed way. For example, Huntingdon’s disease is a genetically transmitted disorder that usually emerges between the ages of 30 and 50, although it can appear at any time since the genetic cause is innately present.

Evolutionary explanations also emphasise the importance of nature as they assume that behaviours or characteristics which increase our chances of survival and reproduction will be naturally selected; the genes for these characteristics or behaviours will be passed on, as they provide an adaptive advantage. For example, Bowlby proposed that children come into the world biologically programmed to form attachments because this will help them to survive. This suggests attachment behaviours are naturally selected, and passed on as a result of generic inheritance (heredity mechanisms).

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