I've experienced exactly what you are talking about John, a few years ago I happened to mention, I can't remember in what context, that one of my grandmas was Indian.
An American reader jumped on that and told me I should say Native American. I was able to reply that actually there weren't any Native American families in Lucknow, India, back in 1887 when Grandma was born.
But that wasn't the end of it.
A British reader got on my case and told me I should be proud of my heritage and identify as Indian instead of letting people think I'm British.
And erase 3 other wonderful grandparents out of my life just like that.
It's such incidents that make me find the whole race debate, as it is being framed, irrational.