Nature and Nurture: Are We Missing a Third Option?

Abstract

In light of my own situation, I have been drawn to question whether all experiences can be explained in terms solely of nature and nurture. This has led me to seriously question the notion of genetic determinism. While the interplay of nature and nurture may be far more complicated than we currently understand, the uniqueness of my situation suggests there may be more to the story which led me to wonder whether, in fact, there may be a third option: nature + nurture + ‘?’.

This thesis focuses on two areas. Firstly, genetic determinism—the notion that our genes determine who and what we are—is examined. Genetic determinism is the basis of the ‘nature’ part of the dichotomy. Secondly, if the genetic determinism component of the nature and nurture equation is found lacking, what is it that might be missing?

There are two possible candidates for the third option: emergence and chaos. Emergent properties are those which arise out of the interactions of the components of a system. These properties are an “extra piece” that is present when the system (such as the human body) functions as a whole but which cannot be identified when the system is examined in its component parts (such as organs or tissues). Chaos is behaviour within a system that we cannot predict from looking at the system’s initial conditions. For example, fluctuations in the levels of regulatory molecules within a cell can result in fluctuations in gene output or the increased variation in dendrite formation of melanocytes due to an organism having only one functional copy of the tumour-suppressor gene neurofibromatosis type 1 (NF1), instead of two (haploinsufficiency).

Both of these concepts represent new areas of scientific inquiry. While the evidence for emergence is interesting, this thesis concludes it is too early to be drawing any significant conclusions about its role. The evidence supporting the role of chaos is also limited but it is compelling. This thesis concludes that chaos may be the third option in the nature and nurture debate, although its role is likely very small.

Many arguments in bioethics are launched from a position of genetic determinism on the assumption that after an assessment of an individual’s genes, we can draw conclusions about who they are now and who they will be in future. To examine the questions posed by this thesis the areas of genetic testing, genetic modification and cloning are examined as examples of the role of genetic determinism in bioethics. This thesis is significant for bioethics because it demonstrates that one of the tenets of many bioethical discussions is based on a poor understanding of science. In addition to the areas examined in detail, the implications of this thesis for neuroimaging, violent or criminal behaviour, chemical castration of sex offenders, mental illness and synthetic biology or artificial life are also briefly discussed