Well, yeah. My mother still hasn't come to terms with anything remotely nonmonogamous, despite my first marriage many, many years ago being open to outside flings. I learned then just not to talk to her about my relationships. I don't hide anything, I just don't talk about it with her.
Some of the folks I work with know we're poly. I still don't mention it in general conversation as I'm uncertain as to whether it would cause any problems. It's not that I love my job--I don't and I don't expect to be in the position on anything approaching a permanent basis--I'd just rather leave it by choice rather than having had problems with coworkers or management over how I live my life.
It's also why I don't discuss religion most places and so forth. I have enough difficulties as it is, I don't need to create any I can simply avoid.
Once poly gets to be known and accepted more widely, then I'll discuss it more openly with more people in more settings. We can work out legal entanglements slowly and I won't fret. I'd really like social acceptance much more quickly.