I hear you B.!! Although my experience is somewhat different, I get so sick of hearing the same comments over and over from people who think they are original and clever, but don't actually think what they are saying might be offensive. I have wavy brown hair and green eyes. My hubby has straight blond hair and brown eyes. My toddler daughter has insane curly curly bright red hair and blue eyes.
When we are out, just the two of us, and I get the "WHERE did she get that hair?!" its a lot easier to brush off (although annoying, cause it happens EVERYWHERE we go). However, I can't stand it when we are out as a family, and people will literally look from my husband to me, back to my husband and ask it. Like they are possibly insinuating that she is not his. I have seriously had people joke about mailmen, delivery boy etc, or tell my hubby he should check it out, right to our faces!! Who raised these people??!!
My responses varied in the beginning. I would just say " I know, isn't it a trip?" My daughter actually started saying that too =) Or I would say that she got it from my grandfather, which is true, and some people genuinely seemed to want to know. I now use " those irish genes are like kryptonite" which I got from my quick-witted friend. It refocuses their direction, and I think it would work for you too. Just insert your last name in place.
Its funny, I'm sure like me, you realize this type of thing is not the end of the world. We know we should count ourselves lucky that we have healthy, happy amazing kids, but something seemingly so small can get to us so bad. Sorry this note was so long, but it was nice to vent and to realize I'm not the only one who deals constantly with "innocent" comments. Take care girl, hope you figure out a clever response, and just enjoy your handsome hubby and son.