Throughout Proof, Catherine compares herself to late her father, Robert. Robert was a mathematical genius who revolutionized his field, and she worries that she won’t live up to his example. She also compares her sanity to his; Robert suffered from mental illness, and Catherine constantly worries that any unusual thought pattern might be evidence that she shares his disease. This gives Catherine a mixed relationship to heredity: she wants to inherit her father’s genius (and she’s worried that she didn’t), but she doesn’t want to inherit his instability (and she’s worried that she did). An enormous question for Catherine, then, is how much of her life is hers and how much is determined by her family and her genes. And this is especially complicated considering how similar she is to her father: Catherine and Robert share a passion for math, a prickly temperament, and their handwriting is even similar, which leads to real problems when she claims to have written a proof and nobody can tell at first whether she wrote it or he did. But, in the end, the proof is identified as hers—despite all its similarities to her father’s work, Catherine’s work is distinctly her own. This shows that, while she has inherited many traits from her father, Catherine is still able to carve out her own identity. Family and heredity have shaped her but not defined her.
Catherine’s biggest anxiety about heredity is that she’ll develop her father’s mental illness. At the beginning of the play, Catherine expresses this outright. While having a conversation with her dead father, she asks him if this conversation is, in itself, evidence that she’s crazy. After all, she is interacting with someone who isn’t there. During this conversation, she also asks when her father’s illness first appeared (wondering if her own symptoms are appearing in a parallel timeline), and she reveals that she “keep[s] up with the medical literature” on the role of heredity in mental illness. It’s clear that Catherine is terrified that her genes will doom her to a life of similar mental instability. And there’s some evidence that she’s right. Not only does she have a conversation with her dead father (possibly a hallucination), but she also shows symptoms of depression and paranoia. So Catherine certainly shares some of Robert’s traits, but it’s not clear to what extent—just because she’s prone to instability doesn’t necessarily mean she’ll be unstable in the same way.
Catherine also worries about inheriting her father’s genius—namely, that she didn’t inherit enough of it and therefore won’t live up to his illustrious career. Like her father, Catherine has a talent and passion for math—the two bonded over it throughout his life, with Robert encouraging her and helping her hone her skills. While he hoped that she might “pick up where he left off,” she worries that she won’t be able to. By the time he was her age, after all, he had already revolutionized his field, whereas she is merely a depressed college dropout who has just lost the one person who believed in her: her dad. But over the course of the play, it becomes clear that Catherine and her father are more similar than she initially lets on. Like her father, Catherine has done groundbreaking mathematical work before the age of 25, she just hasn’t told anyone about it yet. And when she finally reveals the proof she wrote to Robert’s former student Hal, he affirms its significance—it’s the kind of work that only a genius like her father could do.
But no matter their similarities, the play asserts that Catherine is her own person—she’s not merely a replica of her father. This becomes clearest near the end of the play when Hal is struggling to determine who actually wrote the proof. He initially assumes that it’s Robert’s work, since the handwriting looks like Robert’s and, more to the point, the mathematical genius that it would require to write such a proof seems to point only to him. That Catherine’s work initially seems indistinguishable from her father’s underscores their similarities. Yet once Hal spends more time with the proof, he sees indications that Catherine is actually its author. For one, the mathematical style is different—it’s less elegant than Robert’s style and it uses new math techniques that Robert wouldn’t have known. In addition, Robert dated all his writing, but this proof has no dates. With this, the play shows that Catherine—despite being so much like her father—has an identity of her own.
Furthermore, Hal suggests that the similarity between Catherine and Robert’s handwriting is normal; “Parents and children sometimes have similar handwriting,” he says, “especially if they’ve spent a lot of time together.” This hints at a crucial point: that genetic heredity isn’t the only form of familial influence. Catherine’s handwriting doesn’t resemble her father’s because they’re blood relatives—it’s because they spent so much time together when he was alive. Maybe, then, her life resembles her father’s both because of her genes and because he influenced her. This suggests that she’s not necessarily fated to follow his patterns, no matter how similar they seem. As Hal tells her, “Maybe [she]’ll be better” than Robert.
Family and Heredity ThemeTracker
Family and Heredity Quotes in Proof
ROBERT: You see? Even your depression is mathematical. Stop moping and get to work. The kind of potential you have—
CATHERINE: I haven’t done anything good.
ROBERT: You’re young. You’ve got time.
CATHERINE: I do?
CATHERINE: By the time you were my age you were famous.
CATHERINE: You died a week ago […] You’re sitting here. You’re giving me advice. You brought me champagne.
CATHERINE: Which means…
ROBERT: For you?
ROBERT: For you, Catherine, my daughter, who I love very much…It could be a bad sign.
HAL: […] When your dad was younger than both of us, he made major contributions to three fields: game theory, algebraic geometry, and nonlinear operator theory. Most of us never get our heads around one. He basically invented the mathematical techniques for studying rational behavior, and he gave the astrophysicists plenty to work over too. Okay?
CATHERINE: Don’t lecture me.
CLAIRE: Living here with him didn’t do you any good. You said that yourself.
You had so much talent…
CATHERINE: You think I’m like Dad.
CLAIRE: I think you have some of his talent and some of his tendency toward…instability.
ROBERT: […] I’m not doing much right now. It does get harder. It’s a stereotype that happens to be true, unfortunately for me—unfortunately for you, for all of us.
CATHERINE: Maybe you’ll get lucky.
ROBERT: Maybe I will. Maybe you’ll pick up where I left off.
CATHERINE: Don’t hold your breath.
ROBERT: Don’t underestimate yourself.
HAL: I’m a mathematician […] I know how hard it would be to come up with something like this. I mean it’s impossible. You’d have to be…you’d have to be your dad, basically. Your dad at the peak of his powers.
CATHERINE: I’m a mathematician too.
HAL: Not like your dad.
CATHERINE: Oh, he’s the only one who could have done this?
HAL: The only one I know.
HAL: […] Your dad dated everything. Even his most incoherent entries he dated. There are no dates in this.
CATHERINE: The handwriting—
HAL: —looks like your dad’s. Parents and children sometimes have similar handwriting, especially if they’ve spent a lot of time together.
HAL: There is nothing wrong with you.
CATHERINE: I think I’m like my dad.
HAL: I think you are too.
CATHERINE: I’m…afraid I’m like my dad.
HAL: You’re not him.
CATHERINE: Maybe I will be.
HAL: Maybe. Maybe you’ll be better.