Hmm, I was half-afraid, half-expecting such reactions to appear... but it's completely normal and I understand why. However, I need to say that a big family like Maddox's cannot have been held together without a certain degree of authority, something that parents might find a hard time to relinquish as the time passes, and kids turn into grownups.
I also want to point out that even the most loving parents can - and will - say things they might come to regret later. I've seen it happening a hundred times and more. When Maddox's mom says 'you can't be gay', it sounds like she's not allowing it, but the meaning would be 'it's not possible because I've known you to be someone different than what you're telling me right now'. Vern, as the oldest, has the most experience with the parents, hence his advice to Maddox.