people fought and killed their family members in the last civil war in the US. and in every civil war ever.

I will here reference lyrics from the song "we want freedom" by dead prez:

Yeah, yeah Imagine havin' no runnin' water to drink Chemicals contaminate the pipes leadin' to your sink Just think, if the grocery stores close they doors And they saturate the streets with tanks and start martial law Would you be ready for civil war Could you take the life of somebody you know, Or have feelings for if necessary? I got cousins in the military But far as I'm concerned they died, when they registered