Nature versus nurture in human development

Nature and Nurture in the Current Developmental Psychology Research Literature

Developmental Psychology

The "nature vs. nurture" debate has resided at the heart of developmental psychology for the past several decades. From the moment that Crick and Watson discovered that genetic information is passed along through cellular structures and that this information has a role in determining who we become, scientists and ethicists alike have argued over what holds primacy, the role of genetic inheritance or the role of environmental conditioning. Applications of the debate have been found in related fields as varied as neurological science, linguistics, sociology, psychopathology, education, and gender studies, but it is in developmental psychology proper, perhaps, that the debate seems to hold a place of particular importance. If DNA is destiny, then what we do around the fetus, infant, and child seems less important. However, if nurture is primary, then the environmental structure we create are of crucial importance. It is important to understand the general contours of the debate and to know what current thinking around the subject says in order to know how to approach the very modalities basic to the discipline.

In this, paper, the debate between nature and nurture will be reviewed briefly and the current data on the debate in the research literature will be highlighted in order to present the current best findings, thereby informing the study of developmental psychology on this key concern.

The essential thrust of the nature vs. nurture debate revolves around the role that genetics play in determining human attitudes and behavior. The human genome project and other studies showed that genes play a very large role indeed, with different genes having been identified for all kinds of behaviors and attitudinal states such as depression, fear, and the like. This suggested that there was a genetic endowment for virtually every behavioral or attitudinal state. In fact, for much of the last half-century, the consensus view among scientists was that inheritance was the major contributor to destiny, even if we didn't always understand how genetics played out. A second consideration has been, however, that environment also affects behavior. Conditioned responses have been shown in numerous studies to accommodate for basic genetic traits, as in cases in which stroke victims or others have been helped to overcome brain-damage-induced deficiencies through rehabilitation. Still, however, the thinking for much of the past generation was that when conditioning seemed to have an impact, it simply covered over or compensated for genetic traits. If left to their own devices, the gene endowments would likely re-emerge dominant. Richardson (2000) summarizes this kind of difficulty with a dual-influence model, when he claims that for most of the history of the nature vs. nurture debate, it has been assumed that the two variables worked independently of each other and that when genetics had an impact, it was from a position in which it arrived on the job fully formed and ready to go to work (1-2). In other words, the idea that there was a systemic relationship between genetics and conditioning, in which genes themselves can be influenced by environmental conditioning had not occurred to anyone.

In recent years, however, this has become the dominant model. University of Iowa professor John Spencer, for examples argues that

"People have tried for centuries to shift the debate [between nature and nurture]one way or the other, and it's just been a pendulum swinging back and forth. We're taking the radical position that the smarter thing is to just say 'neither' -- to throw out the debate as it has been historically framed and embrace the alternative perspective provided by developmental systems theory." (Science Daily, 2009)

And research does seem to suggest that such a view is valid. Jay Belsky and Michael Pluess (2009), for example, review the related literature concerning the concept of plasticity to show that children having clear susceptibility to negative programming also show susceptibility to positive programming. They argue that the interaction between inheritance and environment can be seen in both cases, and that the reaction doesn't just go one way. It can actually be reversed. This suggests that genes are actually reacting to environment in a systemic fashion.

Margaret Beale Spencer and Vinay Harpalani (2003) argue that a "behavioral genetic" model is the best model available at present to show how nature and nurture work together. However, they claim that no one really seems to know how such a systemic model actually works. They offer one possible variant, consisting of a process-oriented approach in which genes are continually faced with new challenges as a result of the environmental conditions relevant to the person's particular life stage. The genes change in response to these challenges, which results in a new behavior being reflected. This behavior and this new gene state then meet new environmental challenges and make their responses. In this way, a continuous cycle of genetic responses and environmental conditioning takes place.