There are many ways to describe and explain living processes; of these reductionism is one of the most powerful. Reductionism as a method of experimentation yields valuable insights but fails as a universalising philosophy. Genetic reductionism begins with the idea of ‘hidden determinants’ of phenotypes, but there is no direct gene–phenotype link and the very concept of ‘a gene’ is problematic. Molecular epigentics has revealed the complexities of gene expression during development. However, for evoutionary biologists genes are often no more than formal accounting units, rather than deoxyribonucleic acid sequences. Autopoiesis, the process by which an organism constructs itself out of the raw material of genes and environment, is a preferred concept to arbitrary nature/nurture partitioning. Yet there are strong ideological pressures toward adopting naïve genetic determinist metaphors.

Key Concepts:

• Biologists ask many different questions of living phenomena, and the types of answer they seek depends on the purposes for which the question is asked.
  
• Reductionist methods are very productive but reductionism as philosophy can be misleading.
  
• The historical development of science has given primacy to reductionist explanations.
  
• The concept of ‘a gene’ has changed over time and is now dissolved into variously edited DNA sequences.
  
• There is no one‐to‐one correlation between gene and phenotype.
  
• Epigenetics studies the ways in which cells regulate gene expression during development.
  
• Living organisms are not passive expressions of gene activity but construct themselves using the raw materials of their DNA and the environment during development – this is autopoiesis.
  
• Genetic determinism has become a fashionable ideology in response to the growth in genetic knowledge and the multiple crises of our present society.