[Clara's] dad had wanted her to study medicine instead of arts. Medicine was what he'd wanted to study when he'd been young, only his elderly parents had forced him to do accounting instead. (4.3)
Too many parents make the mistake of seeing their children as extensions of themselves rather than separate individuals. This seems to be Charlie's problem, as well as Jessaline's parents'. Wanting your kids to follow in your footsteps or have the opportunities you didn't get is nice—but your kids have to want it, too. Charlie may think he's doing what's best for Clara, but he's actually continuing the vicious cycle his parents created.
When [Lily] suggested he get someone to do the mowing, a small spurt of rage had flared hotly against his ribs. She thought he was past it! He could hear it in her voice. Past mowing a bit of grass himself! (5.3)
In Pop's defense, Lily really should know better than to get between an eighty-year-old man and his independence—no one ever told a guy like Pop to stop mowing his lawn and had it end well. Still, Stan clearly suffers from the prideful edge a lot of dudes his age get as they struggle with the inevitability of getting old.
Parties in their family always seemed to end in fights. Or even start with them, like this one would if Lonnie came along and Pop was still disgusted with him. (12.57)
Parties in the Samson family largely fail because they're a clash of a ton of prideful personalities—a whole lot of people trying to convince each other that it's their way or the highway. This may be pretty normal behavior, but it can turn deadly if the patriarch owns an ax and isn't afraid to use it.
Sometimes Lily felt there was an aura about her, a scent of danger as well as cooking smells that hung about her hair and skin and clothes, so that people, without knowing they were doing it, backed away from her. (13.11)
Lily's biggest problem isn't looking like Pop or allegedly smelling like a kitchen. Nope, Lily's biggest problem is Lily. She's a mega drama queen in a paranoid sort of way, and this behavior in itself is prideful; she assumes the whole world is paying attention to her when the reality is that they probably aren't. Unfortunately, Lily's self-importance actually causes her to feel unhappy about herself and how others may perceive her.
"But then he'd be in your Year!" cried Lara, and there were sounds of disgust from almost all the girls. Who wanted to go out with a boy in your Year? A boy you'd known since primary school, and possibly even kindergarten? Who'd had disgusting habits when he was a little kid, even if he'd curbed them now. (16.7)
For boy-crazy sophomores who desperately want guys to notice them, these girls sure aren't approaching things logically. If they would stop thinking they're too good for boys they went through childhood with, they might realize they've changed and open up a new door for potential boyfriends.
Her mother stared straight into her daughter's eyes, and Lily suddenly felt that Mum knew all abut her crush on Daniel Steadman, knew how she lay awake at nights and thought of him. (19.39)
What is it about having a crush that makes girls want to keep it from their moms? They're moms, which means they were once love-crazy teenagers themselves. They have a sixth sense about these things. This, of course, makes any of Lily's prideful attempts to conceal her emotions totally irrelevant.
[Lonnie] was torn about Nan's party. He wanted to go for her sake and because he loved that little house up in the mountains […] But how could you go to a party for someone who'd written you off? […] Pop might not have cut his head off, but he'd wounded him all the same. Banished him. (22.5-6)
It's amazing what people will sacrifice just to prove they're right. Somehow, Lonnie thinks that staying away from Nan's party—even though he really wants to go—will make some kind of statement to Pop. Actually, Lonnie's the real loser in this scenario. By not going to the party, he would not only miss the celebration, but still be consumed by anger. Luckily, both Lonnie and Pop come around.
[Charlie] stood stock-still, his fists clenched by his side, waves of rage and shock rolling through his blood. This was what they left home for, he thought bitterly, these girls. (22.45)
What exactly is Charlie angry about when he catches Clara making out with Lonnie? Is he upset because his daughter could be making a mistake that could affect the rest of her life? Or is he angry because she's making him look bad in front of his workplace? We know Charlie has a problem with wanting people to fit his rigid standards, so we're betting on the latter.
Stan didn't soften, as May had hoped he would: he didn't leap up from his seat and hurry out onto the station and then on down the street, searching for his grandson's new home. All that happened was that Stan gave a guilty start and turned his head away. (26.2)
May's humility and forgiving spirit make Stan's anger toward Lonnie seem even more ridiculous. The fact that he thinks about stopping at Lonnie's proves that he's feeling guilty, even if he doesn't want to admit it.
"She came to Mercer Hall when I was out and left [spring rolls] for me. And I didn't call to thank her because I was so mad she'd been there without even telling me. And you know, I told you, how she wants to see my room, how she'd wanted to see it for months and months and I've put her off and—I'm a bully!" howled Clara. "That's what I am—I'm a bully just like Dad!" (39.19)
A big part of the book is characters like Clara, Lonnie, and Lily learning that although they may think they know what's what now that they're teenagers and/or in college, they're human and fallible just like everyone else. They may think they're parents don't get it, but in reality, there's just as much that they don't understand themselves, too.