The biology behind your social attitudes

My article on April 4th, arguing that gender-specific behaviour is more a biological than a social construct, elicited a large reaction from readers. Many people hanker after a human nature that is endlessly malleable under environmental influences, and resist evidence that supports any biological hardwiring of human behaviour. However, biology undoubtedly plays a prominent role, and not only in gender-specific behaviour.

Our basic biological identity is located in our genes. Any traits we have that are biologically determined, or biologically influenced, are encoded in our genes, and these traits/influences will be inherited by our offspring. Study of the heritability of human behaviour and capacity is not new, of course, but such studies have been concentrated in relatively few areas. The heritability of human intelligence (IQ) has been thoroughly researched – overall, about 50 per cent of the variability in human intelligence is due to inheritance and 50 per cent to environmental factors (for example, educational opportunity or social conditions).

On the other hand, although people differ greatly in their social and political attitudes, little research has been carried out to investigate where these differences in opinions come from. However, a growing body of work, reviewed by psychologists Gary Lewis and Timothy Bates in The Psychologist , Volume 26, Number 3, March 2013, demonstrates that biology strongly influences our social and political attitudes.

Much of this research relies on twin and family studies that can separate the relative genetic and environmental influences underpinning individual differences for a particular trait. Identical twins are nearly genetically identical whereas ordinary (fraternal) twins are no more genetically related than non-twin siblings, sharing half their variable genetic matter. Consequently, if two identical twins, reared together in the same family are more similar to each other than two non-identical twins reared together, the greater similarity of the identical twins is attributed to their greater genetic similarity. The greater the difference between identical twins and non-identical twins, the larger the effect attributed to genetics.

Such twin studies played a pivotal role in knocking down the old “refrigerator mother” hypothesis for autism – the notion that autism is caused by a lack of maternal warmth. An understanding of autism required a study technique capable of distinguishing environmental and genetic influences. Such studies were performed in the 1970s.

Lewis and Bates report that the earliest genetically informative study of socio-political attitudes was published in 1974, finding that self-reported radicalism (as opposed to conservatism) and tough-mindedness are substantially influenced by hereditary factors. These findings were unpopular and were largely ignored, despite their publication in the most prestigious science journal, Nature . Twelve years later, these findings were replicated in another study and broadened to include a range of issues including gay rights, abortion and the death penalty. The findings were again largely ignored, and it wasn't until 2005, when they were reintroduced to an influential social and political science audience, that they finally strode on to a mainstream stage.

Lewis and Bates cite further studies that demonstrate that the decision to vote in elections (voter turnout) is substantially heritable and also that religious attitudes are significantly underpinned by genetic factors. Interestingly, while strength of religious belief is heritable, the religious denomination chosen is almost entirely attributable to environmental factors. Overall, the study of the genetic basis for social and political attitudes is only in its infancy. Researchers are still a long way from identifying particular genes that influence such attitudes and it is probable that any particular heritable attitude is influenced by a large number of genes.

People obviously differ in their views on how society should be run. Despite the importance of these attitudes and their potential for causing problems, their origins are poorly understood. As Lewis and Bates point out: “Research in this area has traditionally focused almost exclusively on environmental determinants of social and political sentiment but it now seems clear that understanding political divides will require biological as well as social explanations”.

William Reville is an emeritus professor of biochemistry and public awareness of science officer at UCC. http://understandingscience.ucc.ie