In APS, development is not understood as the execution of a pre-written genetic program.
Genes do not contain a complete blueprint specifying the final form of an organism. Genetic activity can be indispensable to development, but the relation between genetic activity and developmental outcome is realised through developmental processes whose relevant dependencies must be established for the biological case concerned.
Depending on the explanatory target, these dependencies may include cellular interactions, signalling processes, material and mechanical conditions, physiological relations, environmental conditions, or constraints affecting developmental activity. No fixed inventory of such dependencies is assumed to be required in every developmental system.
Development is therefore not adequately characterised as the linear unfolding of encoded instructions. Cells and tissues can respond to positional conditions, signalling environments, mechanical relations, metabolic states, and interactions with other components of a developing system where these make a material difference to the developmental process concerned.
Developmental trajectories can consequently differ even where important genetic features are shared. Such variation may involve plasticity, compensation, altered developmental pathways, developmental disruption, or other outcomes, but none of these relations should be treated as a universal property of development.
Rejecting genetic execution does not require replacing genetic control with an equally universal organisational or environmental program. Genes remain materially important components of developmental explanation, while the additional processes and relations required to explain a particular developmental outcome depend on the explanandum.
Key point: development is not the execution of a complete genetic blueprint. Genetic activity operates within developmental processes whose relevant dependencies and consequences must be established for the biological case concerned.