This examination of the genetic nature of Deryniness points up another important point: that the myth of being only “half-Deryni” (having only one parent who is Deryni) is exactly that—a myth. Since the X' is the only factor governing full Deryni inheritance, Deryni like Morgan and Duncan, with Deryni mothers only, are just as much Deryni as Kelson, Charissa, or any other “full Deryni.” Since Deryniness is inherited in its entirety from either parent, there is no half-way measure. One is either Deryni or not. The prime factors make all the difference.

A GENETIC RETROSPECTIVE, THIRTY YEARS LATER

Over the past three decades, many readers of the Deryni Saga have spent many hours puzzling over the genetic aspects of what makes a person Deryni. Like them, I have become aware that the matter is far more complicated than I posited as a fledgling author, pretty much fresh out of medical school (and with the genetic understanding of the early 1970s), and while the Deryni universe was still taking shape—and it is still evolving. As the back history has gradually unfolded, I have developed further and perhaps more plausible explanations for the Deryni’s extraordinary powers.

But the key concept, around which nearly all of the key conflicts in Deryni history seem to revolve, always seems to come back to some aspect of a single question: Just what is it that makes a Deryni? Today, well into the first decade of the twenty-first century, it has become increasingly obvious that the question is far more complicated than a simple sex-linked gene marker.

We know, for example, that people with Deryni powers—or at least with powers like Deryni—do crop up from time to time, both male and female—and not just from plot necessity! We also know that there are talents within the broad spectrum of Deryni powers that are not accessible to all Deryni. The Healing talent would appear to be the most notable of these, surfacing only rarely—and the bearers of this gift usually are male. (We know that one of Evaine’s daughters was a Healer—and that this was remarked upon, even before her birth. The legendary Jodotha was also a female Healer.) A possible explanation for this apparent imbalance is that the emergence of this particular talent in females renders the carrier more fragile than her male counterparts, less apt to survive to adulthood.

The Healing talent would appear to be further differentiated, in that some Healers can block the powers of other Deryni, even other Healers—but not all Healers can do this. Indeed, we have met only three, thus far: Rhys Thuryn, Tavis O’Neill, and Sylvan O’Sullivan. Were these men anomalies, even among their own kind, or is it simply that no Healer had ever thought to use his powers in this manner before Rhys discovered it quite by accident? We know that Dom Queron tried and failed to emulate what Rhys had accomplished—and he was a highly trained and skilled Healer as well as a powerful Deryni. (For that matter, we must consider whether the blocking ability is even unique to Healers. What if certain non-Healer Deryni can also block powers, but we simply have not encountered any of them?)