Peer Pressure
Peer pressure—the phenomenon of members of a peer group exerting influence on someone—is an important theme in DNA. Peer pressure enters the story when Kelly reveals that the group of teenagers at the center of the play have harassed their peer, Adam, to the point of his presumed death. As Mark recounts how Adam fell into a deep shaft at the top of a hill, the audience realizes that what began as the group mocking Adam's desire for companionship transformed into something uglier when the friends made Adam risk his safety and dignity with increasingly dangerous and humiliating stunts. Peer pressure also plays a significant role in the aftermath of Adam's death: Rather than alert the police or the school or Adam's parents, the teens pressure each other into keeping what happened a secret so they can avoid consequences. When Brian or Leah express a desire to do the right thing and confess, they are pressured by the others to continue propping up the lies. But while the group manages to avoid facing legal consequences for their actions, Kelly shows how the collective pressure the teens exert on each other leads to the group's collapse; by the end of the play, Richard discusses how each friend has splintered off, most of them ostensibly driven mad by the cover-up.
Empathy
Empathy—the ability to understand and share another being's feelings—is a crucial theme in DNA. Kelly touches on the theme most explicitly at the end of Scene One when Leah talks about bonobos' ability to feel a fellow bonobo's pain when one of them is injured. In her indirect way, Leah's commentary reveals that she is working through her thoughts about the human capacity for empathy, which Phil—having coldly and calculatedly devised a plan to cover up Adam's death—would appear to lack. As the play goes on, the ability to understand and share other people's feelings proves to be the dividing line between members of the group. While the more sensitive characters, Leah and Brian, wish to put a stop to the cover-up at different points, characters like Phil and Cathy reveal their sociopathic indifference toward the innocent people being harmed as a consequence of their plot. At the end of the play, Leah weeps as she tries to make peace with the fact her boyfriend has ordered Cathy and Brian to kill Adam rather than bring him back to his parents. Having discovered that she can't be with a person who lacks all empathy, Leah leaves without saying goodbye.
Sadism
Serving as a contrast to empathy is the theme of sadism—the tendency to feel pleasure in response to another being's suffering or humiliation. Kelly establishes the theme when Cathy first appears on stage: Rather than weep like Brian or panic like everyone else, Cathy grins because she is excited by the crisis. Kelly builds on the theme when Mark explains how entertaining and pleasurable it was to see the fear on Adam's face as they punched him, stubbed out cigarettes on his skin, made him run across traffic, and pelted him with stones. Leah also addresses sadism when talking about the "evil" of chimpanzees, who go to war with each other and seemingly delight in conquering enemies they sometimes cannibalize. While Phil reveals a disturbing lack of conscience characterized by indifference, Cathy distinguishes herself because she gets a thrill from immoral behavior. Toward the end of the play, Cathy's sadism has developed to the point that Brian remarks on her love for violence, which puts her in a position to be "running things" at the top of the school's social hierarchy. According to Richard, people believe she has even cut off a first-year student's finger.
Conspiracy
Conspiracy—the action of secretly plotting in a group to do something unlawful or harmful—is a dominant theme in DNA. Kelly explores the theme through the teenagers' collective decision to cover up the truth of Adam's disappearance. The teens panic over what to do because they know they have all contributed to Adam falling into the shaft; to remedy the crisis in a way that avoids culpability, the group follows Phil's elaborate plan to mislead the police with a phony child-abduction case. However, the conspiracy becomes even more complicated when Cathy uses DNA to frame an innocent postman who fits their invented description of a potential kidnapper. Later, the group discovers another problem: Adam is alive and has been surviving in the woods for weeks. But rather than admit to their cover-up, the group decides—at Phil's urging—to make Brian suffocate Adam and to let an innocent postman go to prison for Adam's death. Ultimately, Kelly depicts the way in which a conspiracy tends to involve not just an initial lie or criminal act, but subsequent lies and criminal acts that become necessary to prevent the conspiracy from being exposed.
Fear
Fear is another major theme in DNA. The theme first arises when Lean and Phil are sitting together in Scene One. Without yet knowing of the crisis engulfing their friend group, Leah comments on the ambient terror that pervades their social environment: "I'm scared, they scare me, this place, everyone, the fear, the fear that everyone here ... lives in, the brutal terror." Fear is also a major factor motivating the group's unwise decision to cover up Adam's death: Afraid of facing consequences, the friends band together to protect each other; however, they introduce more fear by using threats to ensure everyone sticks with the story, such as when Phil threatens to kill Brian unless he positively identifies the innocent suspect. Kelly also touches on the theme of fear when Mark describes how the group tortured Adam in the lead-up to his death. Annoyed by Adam's desire to hang out, Mark and the others went to increasingly cruel lengths to break Adam's composure and expose the terror in his heart.
Exploitation
Exploitation—the action of taking advantage of someone who is being unfairly treated—is another important theme in DNA. The theme first arises when Mark details how the group took advantage of Adam's compliant nature and longing for friendship to entertain themselves at his expense. The theme comes up again when the friends discover that a postman fitting the description Brian gave has been arrested because his DNA was found on Adam's jumper. Rather than intervene to exonerate the innocent man, the group willingly exploits the situation because it means they are less likely to be found out if the postman goes to jail for their crime. Exploitation also arises late in the play when Phil realizes that it would be best for the conspirators if Adam really was dead. To remedy the situation, Phil takes advantage of Brian's medication-induced obliviousness to make him suffocate Adam with a plastic bag.
Innocence
Innocence—the state of being naive and uncorrupted—is a crucial theme in DNA. Kelly begins exploring the theme with Brian's introduction to the stage: In contrast to Cathy's grinning, Brian cries over the deeply upsetting crisis. Brian is also the only character who suggests telling someone about what has happened to Adam—a wise suggestion the others consider naive. As the play goes on, Phil uses Brian's innocence to the group's advantage by making Brian lie to the headmaster about a fat postman flashing his genitals in the woods. Brian is then put through the ordeal of having to repeat the lies to the police. Brian cries through it all because of the guilt he feels, but the authorities perceive his tears as the expression of an innocent who has been caught up in a tragic event. Kelly shows how the distressing experience corrupts Brian, who is eventually put on heavy medication to numb his feelings. While the drugs make Brian stop crying, his innocence persists as he dissociates from reality and repeatedly fails to grasp the seriousness of what's happening around him. In this ultra-naive state, Brian can be fooled into suffocating Adam under the pretense that they are playing a game.
