If you disagree with his choice, then feel free to tell him why, and let him think about your reasoning. You can always throw out a disclaimer stating that his choices are his own.
It sounds like you already have excellent family discussions. If he feels strongly enough to wear political shirts, then by all means, let him. His friends will let him know if they think it is inappropriate.
GUEST'S ANSWER: Richard Rosser, author of “Piggy Nation,” a series of books, a cartoon and more on etiquette: In these days of political apathy among voters of all ages, why would you want to stifle your son's interest by censoring his political views?
As I see it, you have three options: 1. Ban the T-shirt and risk alienating your son. 2. Let him wear the shirt and risk being embarrassed in public. 3. Get your own shirt that says, “Views and opinions expressed by my children do not necessarily reflect the official position of the (insert your last name) family.”
Good luck and congratulations on raising a child who's interested in the political process!
Callie Athey is 20-something, Lillie-Beth Brinkman is in her 40s, and social columnist Helen Ford Wallace is 60-plus. To ask an etiquette question, email firstname.lastname@example.org.