The topics are definitely fringe but I'm sure you could find some forum or site that discusses it but I think you have things backwards. It's not that most people wouldn't dare to talk about these ideas in polite company. It's that the people who hold these beliefs aren't polite. Their personalities so abhorrent, vitriolic and unsympathetic. They hold such archaic views, reminiscing about a past that would benefit them at the expense of others.

To use eugenics as an example. Those who speak about it always, without exception end up isolating a single group that they believe is inferior. These people often hold adjacent beliefs that make the lives of other humans significantly harder, to say the least.

This seems like a slippery slope argument, much like those who claimed gay marriage would inevitably lead to polygamy and thus should be banned for fear of making it easier to normalize polygamy in the future.

What? No one is being forced into gay marriage. And as long as they're consenting adults they can have whatever non traditional arrangements they want.

I'm having trouble understanding where this slippery slope is coming from. It's one thing if you were talking about assisted suicide, I can see the argument there, but eugenics is something that is forced upon the population. And no, having to watch two people of the same gender kiss on TV is not forced.

> And as long as they're consenting adults they can have whatever non traditional arrangements they want.

An extremely large proportion of the US population would not agree with this if you include polygamy in "whatever non traditional arrangements they want".

Why? Are they being forced to marry the polygamists?

Considering I'm not presently a US citizen you probably shouldn't be asking me.

I have met a lot of people who support some form of eugenics that do not support "isolating a single group that they believe is inferior". I think that is unfair criticism unless you're only restricting eugenics to sterilizing a group based on a single characteristic.