Criminal behaviour is but one behavioural tendency for which a genetic influence has been suggested. Whilst this research certainly raises difficult ethical questions and is subject to scientific criticism, one recent research project suggests that for some families, criminal tendency might be predicted by genetics. In this paper, supposing this research is valid, we consider whether intervening in the criminal tendency of future children is ethically justifiable. We argue that, if avoidance of harm is a paramount consideration, such an intervention is acceptable when genetic selection is employed instead of genetic enhancement. Moreover, other moral problems in avoiding having children with a tendency to criminal behaviour, such as the prospect of social discrimination, can also be overcome.