I think the common factor involved in most of these may be science fiction.

The connection to transhumanism is so obvious that I shouldn't have to explain it.

The path from science fiction to the Pirate Party is long, but pretty clear. Science fiction is connected with interest in new technology, which leads directly to computers and the Internet, which soon brings you face to face with intellectual property issues in the form of illegal downloading.

Polyamory has the obvious Heinlein connection, but there's plenty of other science fiction that concerns itself with other social structures - and polyamory is a pretty obvious example. Why should Archie have to choose between Betty and Veronica when he could just marry them both if not for the rest of society getting in the way?

Finally, much science fiction takes a perspective that is completely at odds with traditional religions, if not one that is explicitly atheist. For example, Arthur C. Clarke's short story The Star.

So, yeah, that's my story and I'm sticking to it. ;)