This seemed like a bad idea for a thread in the first place. Not surprising it became a vitriol-throwing match.
Usually people get together because they have demographic characteristics in common, and that usually leads to roughly similar politics. That's just how it works. Don't see the point in railing against it.
Very occasionally it works out differently, usually when there are different political directions a given demographic group is torn between - e.g. a childhood friend had a mother who was a solid Labour supporter while his dad defected to the (far-right) National Front. Both were part of working class culture (the marriage didn't last very long after that though).
Or people with different backgrounds can _think_ they have the same politics...but ultimately turn out not to, because those underlying different backgrounds push them in different directions when circumstances change.
Families with huge political disagreements are kind of intriguing though. You wonder how they came to be like that.
Usually it seems to be siblings that end up on opposing sides. We just had all these mad anti-vaxx anti-lockdown demos, many of them attended by climate-change-denier and anti-vaxxer Peirs Corbyn, brother of (supposed) hard-leftist Jeremy. Do wonder how their family get-togethers go. I gather Boris Johnson's family are all 'remainers'.
For some reason that sort of going-to-opposite-extremes seems particularly common with posh families, e.g. Chris and Peter Hitchens, or the Mitford sisters.