No, I'm not saying that things cannot have an independent effect on other things. I'm trying to highlight a category error, as Ryle used to say. One element that contributes to the emergent property of an entity cannot have an independent effect on that entity. Let me try another example. Take cuttings from a plant species, and plant them at different elevations. Although the plants are genetic clones, you will find that they grow to different heights at different elevations. Moreover, if you repeat this with another plant from that species with different alleles, you will find it produces the tallest plants at a different elevation than the first set of plants did. Thus the phenotypic characteristics of the plant (e.g., the height) are not simply a product of genetic instructions; they are emergent properties of the plant's genetic instructions and the particular environment in which the genetic instructions are expressed.
As I said earlier, this is basic stuff you learn in any introductory genetics course. I'm not sure why this is triggering incredulous comments.
Miles