1. "A lot of people, particularly women, still find the idea of their genetic duplicate to be a little unsettling. An old classmate of mine wrote an article in the New England Journal of Medicine last year claiming some relationship between this phenomenon and female self-image" [p. 7]. Do you agree that women are more disturbed by the idea of cloning than men are? If so, what reasons beyond self-image might account for this?

2. Davis spells out the strict guidelines governing human cloning for the Finns [pp. 6-9]. Do these regulations adequately cover all the ramifications of cloning a human life? Does Davis's approach or the reactions of Martha and Terry [p. 10] raise questions about the screening process and other aspects of the system?

3. Is Davis's overwhelming need "to look in the eyes of his daughter's murderer" [p. 62] the normal reaction of a grieving father? How realistic is his assumption that confronting the killer will bring an end to his suffering and restore his and Jackie's happiness?

4. The anti-cloning movement is presented from the point of view of Mickey the Gerund [pp. 46-50, for example]. How does this influence the reader's impression of the movement? To what extent does Guilfoile draw distinctions between Mickey's fanaticism and more sympathetic arguments opposing cloning? What parallels are there between Mickey's attitudes and tactics and those of current anti-abortion protesters?

5. How does the Finns' relationship with each other affect their attitudes about Justin? Is Terry's interest in tracing the DNA donor understandable, or are his motives suspect? Why is Martha so confident that Justin will "get more of her personality from us than he will from some mystery man" [p. 53]? What does her attitude reflect about her attachment to Justin? What does it reveal about her own needs as a mother? At what point in the novel do her feelings change and why?

6. Does your opinion of Davis change as the novel progresses? What particular incidents make him a sympathetic character? To what extent are his difficulties the result of selfishness or arrogance?

7. Is it ethical of Davis to ask Joan to keep his secret [pp. 71-72]? Does she acquiesce because she agrees with his argument? Are they primarily concerned with protecting Justin, or is it equally important to them to safeguard their reputations and their practices? When Davis later lies to his lawyer about the nature of his experiment [p. 163], is he motivated by fear or by what he believes is an inviolable ethical obligation to Justin?

8. When Justin exhibits violent tendencies at the age of seven, Davis dismisses it-"He's a kid. Kids get in trouble"-and declares with confidence "Genetics have nothing to do with it . . . If there's ever been a killer who had a killer for a son, it's because the child learned the behavior from his pop . . . Not because he scored the evil gene" [p. 97]. Why does his certainty gradually erode? Is it possible for Davis to be objective about the nature vs. nurture issue?

9. Guilfoile portrays Justin at various ages, charting both his extraordinary intelligence and his increasing tendency toward violence. How does this technique help to create an escalating sense of suspense? How does it set the groundwork for the ultimate confrontation between Justin and Davis [p. 203]? What does their conversation at this clandestine meeting reveal about each of them? Does the balance of power between them change?

10. Why does Guilfoile introduce the computer game Shadow World? Is it an effective plot device? How does it enhance the themes of the novel? How does it relate to the novel's title? What other interpretations of the title does the author suggest, either directly or indirectly?

11. Justin says, "We're not made up of our thoughts, you know, even though that's the only way most of us can approach the question of identity" [p. 211]. Do you think it is necessary, as Justin maintains, to separate the thinker from his thoughts? Does he offer a credible alternative theory about how humans develop a sense of individuality and self-identity? What role does this, along with his contention that there is no such thing as free will, play in his quest to expose Sam Coyne? How does it affect the decision he eventually makes about his own life?

12. At the conference sponsored by the California Association of Libertarian Scientists, Davis contrasts his approach to that of a colleague: "He suggests that just because we can clone human beings doesn't mean we should. I tell him he's answered the wrong question. If we can do something-to increase health, to increase happiness-doesn't that mean we must?" [p. 179]. Looking at this question in terms not only of cloning but other radical medical procedures, which viewpoint is closer to your own? What experiences, religious belief, or personal philosophy support your position?

13. Mickey and Davis are both driven men, ignoring the law and the rules of society to achieve their ends. In what ways are their motivations and their methods similar? Does the fact that Davis's quest is grounded in science and Mickey's in religious belief make an essential difference in the validity and/or morality of their actions?

14. For Davis, an agnostic, "cloning was never about playing God. It was about replicating God's work, following the blueprints of God's greatest achievement and creating life" [p. 139]. After bringing Justin into the world and watching him grow up, however, Davis is forced to confront the enormity of his actions: "Justin was not conceived in a lab or in the womb but in Davis's mind. He existed because Davis had wanted him to, and what kind of being does that describe if not a god?" [p. 240]. What are the implications of Davis's confusion, both in terms of the novel and in a wider sense?

15. Cast of Shadows ends with a surprising confession. Do you find this a satisfactory conclusion? What light does it shed on the philosophical and scientific "certainties" that inform discussions about the balance between genetics and environment in shaping character? What do you think is the ultimate message of the novel?