It’s because that war was about national (racial) and religious identity. Families usually belonged together then.

In Usa it will be a little different. Race would be one aspect, too. But more so your wealth/social status. A struggle between classes. Rich against poor, and many shades in between.

And maybe young against old. Conservativism has gone too far in both (still so-called) parties. “Left” may not be progressive enough anymore.