Behavior in terms of a motor symphony and central pattern generators, seems now to be dictated by both the individual and nature-genes. In the case of central pattern generation the hybrid crickets' hybrid song shows how there is a genetic basis for some central pattern generation. But also, there seems to be some choice in how one uses or puts together their own motor symphony. As is the case when you start an action but do not complete it, because you do not want to. Thus, some behavior is monitored by the conscious individual, and some is almost completely influenced by genetics.

Careful not to equate CPG with genetics: such capabilities may result from genes or experience (and, most generally, both). Your more general point though is correct and important. CPG activity can be modified by a number of things, of which the "I-function" (in organisms that have it) is certainly one. PG