John Shutt describes it nicely in his post Memetic Organisms:
For the Clojurian I was talking to, implementation inheritance is co-nuclear. There's probably no way for him to accept that it has valid uses.
The meme set carried by the [memetic] organism includes a mass of theories, some of which contradict each other. At the center of this mass is a nucleus of theories that are supposed to be believed (part of what Kuhn called a paradigm). Surrounding the nucleus are theories that are meant to be contrasted with the paradigm and rejected, together with memes about how to conduct the contrast; one might call this surrounding material the co-nucleus.