I guess I consider myself both childfree and poly. I wonder if the same attitude to life in general (ie, that the quality and tone of your living is more a thing of your own creation rather than fulfilling a preset model that everyone else in your culture does) informs both poly and opting out of having children.
Actually, thinking of it now, the worst kind of response is usually the same for both: "It's not natural, you must secretly want to, you must be crazy/in denial, that's just the way it is
, you'll regret it..."
In general I'm enjoying bucking cultural gender norms at the moment - sometimes you only see how firmly ingrained these things are when you actively reject them, ie being moody and emotional, needy and dependent, wanting to nurture kids, wanting to make house, being soft and sweet etc.
While I actually am some of those things, choosing to not have kids (like choosing to be poly) showed me which of them I actually WANT to be