So could the dark complexion of my grandfather -- and of the somewhat darker complexion of many of his offspring (myself included) be attributed to the possibility that he was an "adopted Indian kid"? And who were the parents of these children who were "adopted"?

I don't have solid evidence on this matter. However, a couple of months ago, I had an interesting talk with my dad about it. Of interest here is a pronounced gap between the two front teeth that my two brothers and I all had as children (fixed with surgery). As it turns out, a number of my cousins, uncles and aunts also have this gap, all on the relevant side of the family. My grandfather, Leo also had the gap. It's inherited.

So who had the gap and who didn't? I asked my dad this very question. And the crucial answer, which seems to have surprised my dad, was that the gap seems to be limited to Leo, his children, grandchildren, and great-grand children. In other words, Leo appears to have been genetically distinct in the relevant way from his parents and siblings.

If Leo was indeed an "adopted Indian kid," who were his parents? Again, there is no good answer here. However, an interesting possibility is that he was, in fact, Choctaw, Seminole, or perhaps Creek. For locational information, check any of various web resources on that sad chapter of American history known as the "Trail of Tears." The map below provides at least a glimpse.