Large computer chip circuit board with many large wires


How much of our behaviour is fixed, embedded in the neural networks of our brain? Is it ‘hard-wired’ – set for life – or more flexibly arranged?

Behaviour is complex. No single gene encodes for it, nor does any single event or experience control it. Although we can control some aspects with our own willpower or volition, in the end our behaviour arises from an intricate interplay between our environment, our genes and us.

Science has shown that many patterns of behaviour, including alcoholism, criminality and homosexuality, are somewhat genetically influenced. Our genes even have some control over behaviours that we are unaware of – such as hand clasping (people tend to intertwine clasped hands with either the right or the left side uppermost).

In the case of alcoholism genes may code for certain receptors that bind chemical messengers in the brain, or for enzymes involved in breaking down alcohol. However, our social and cultural upbringing may also affect our alcohol consumption – our parents may be teetotal, for example.

There is bound to be interplay between these factors. We may be born with a genetic predisposition to alcoholism but be lucky enough in our family and social life that we never get tipped over the edge into dependency.

Also, the brain itself is not set in stone. It develops through childhood, goes through massive changes at adolescence, and reaches maturity in our early 20s. Even then the brain retains significant plasticity – it learns and adapts. So if we practise tennis we get better at it.

So exactly how much of our behaviour can be modified, and how much is inborn or fixed by our upbringing? It is hard to say. With humans such a debate is risky, as the notion of ‘hard-wiring’ can be used to support racist or sexist views or other forms of bigotry. On the other hand, in Steven Pinker’s famous phrase, we are clearly not ‘blank slates’ either.

Lead image:

Speric/Flickr CC BY NC

About this resource

This resource was first published in ‘Thinking’ in September 2006 and reviewed and updated in August 2014.

Neuroscience, Psychology
Education levels:
16–19, Continuing professional development