Turning in the Rioters Family members may be estranged over values—or settling old scores.

Politics has long made strange bedfellows. My parents exemplified that cliché, living their differences in public, as leaders of both the local Republican (him) and Democratic (her) town committees, and in private, with frequent full, frank, and occasionally four-letter-word exchanges of views. But they never divorced or drew blood over their differences, simply cancelled out each other’s vote.

When I hear of people identifying their spouses, siblings, parents, children, or…