50% monogamous, 15% poly.
Every lesswrong group I've visited - in the US, Europe and India - had multiple polyamorous people present and discussing polyamory, so I'd be surprised if this poll is way off.
http://lesswrong.com/r/discussion/lw/nmk/2016_lesswrong_dias...
http://lesswrong.com/r/discussion/lw/nor/2016_lesswrong_dias...
http://lesswrong.com/r/discussion/lw/nqa/2016_lesswrong_dias...
http://lesswrong.com/lw/nx2/2016_lesswrong_diaspora_survey_a...
The one that concerns you is that LessWrong is now 18.2% polyamorous. This might just be an effect of increased scope of survey respondents though.
50% monogamous, 15% poly.
Every lesswrong group I've visited - in the US, Europe and India - had multiple polyamorous people present and discussing polyamory, so I'd be surprised if this poll is way off.