There is an explicit belief – evident in jurisprudential literature – that developments in behavioural genetics in the very near future will necessitate a dramatic revolution in common law criminal justice systems. This paper considers what is truly shown by behavioural genetics in relation to free will, and the effect of such conclusions on criminal justice systems which rely upon the concept of free will as a foundation element. This paper ultimately concludes that it is unlikely that criminal justice systems (...) will be shaken – or indeed substantially influenced – by past or future discoveries in genetics. Three major arguments are employed: that theses connecting genetic traits with criminal free will exhibit a naïve conception of partial genetic determinism; that theses connecting genetic traits with criminal free will have been unduly motivated by discoveries in behavioural genetics which are disreputable or misleading; and that even should an unexpected discovery be made exhibiting a strong causal connection between genetics and criminal behaviour, this will not prove to be an intolerable novelty for any criminal justice system which otherwise assumes free will to exist. (shrink)