As parents, we do have to be conscious of the world that surrounds our kids and act accordingly. If we are living outside the norm of the area where we live or our kids socialize, then it's up to us prepare them for the fact that, our lives are NOT what everyone else would consider normal. I've seen this happens more so with religion and some people will be self-righteous to the point of cruelty. On the flip side, it is also our job to inform our children that just because we are living what would be considered a "normal" life, others may not live the same way and that's okay. There are kids that DO have more than two parents, there are step-parents, grandparents acting as parents, adoptive parents, etc.
As for teenagers - lets face it as a parent, it doesn't take much to piss off and embarrass a teenager. You could be as inconspicuous as you like and some teenagers would still be embarrassed by their parents, especially girls.