There are attempts to draw closer and more instructive parallels between computational systems and biological development. In particular, Roger Sansom has made a sustained and detailed attempt to develop close and instructive parallels between biological development and connectionist computational models (Sansom 2008b,a, 2011). This view has the merit of recognising that there is no central control of development; organisms develop as a result of local interactions within and between cells. However, the most promising ideas about program-development parallels seem to us to be ones that point to an apparently close analogy between processes within cells, and the low-level operation of modern computers. One crucial kind of causal process within cells is cascades of up and down-regulation in genetic networks. One gene will make a product that binds to and hence down-regulates another gene, which is then prevented from making a product that up-regulates another… and so on. What we have here is a cascade of events that can often be described in terms of Boolean relationships between variables. One event might only follow from the conjunction of another two, or from a disjunction of them. Down-regulation is a kind of negation, and there can be double and triple negations in a network. Gene regulation networks often have a rich enough structure of this kind for it to be useful to think of them as engaged in a kind of computation. Computer chip “and-gates”, neural “and-gates” and genetic “and-gates” have genuine similarities.