When I told my parents a few years back, I had done very elaborate preparations for Mabon; I cooked the entire day's meals from scratch (went through around 40 apples that day), did crafts, set up activities for the family to participate in, and did a presentation about it. At the end of all of this, I told them that I was a witch who followed an eclectic path.
My family didn't comment. Rather they acted like I had never made the remark and proceeded to praise me on the Carmel apples (as I had made them Carmel apples to eat as I told them). It was surprising the extents they have gone through to erase it from their minds. Even now, several years after, we have only talked about it twice.
I would say that I had a pretty good experience in comparison to what can happen. My family was passive, but many families can also be aggressive, or supportive. I've heard experiences ranging from getting removed from the family, to family members converting over.
All in all, I would recommend that you asses your situation and see if it would be right. You really should not force it, as that will almost always end in a way you don't desire. Try "testing the waters" so to speak. Try to get a conversation started about what your parents think and know about modern magical practices, and if they are accepting of them. Perhaps you could even bring up the fairly recent "Fox news" issue and see what their thoughts are on the matter. (The video link is provided below). Either way, this site offers some helpful pamphlets you could print out and give to them, so they don't have any misconceptions of your practices:
And this is the link to the Fox news video if you care to show this to them:
I wish you the best of luck if you wish to go through with it. Hope all goes well.