My housemate did it with a sibling and discovered some differences, so I was curious to know if I took after one side or another - and my grandmother's mother died when she was only 13 and back in those days (1913) it wasn't unusual for relatives to lose touch. All I know is what my grandmother told me and I'm sure there's a lot she didn't know. She was close to her paternal grandmother - and it's that line of the family that was traced in that book.
I was particularly close to that grandmother - and know my Dad's siblings and first cousins quite well. My grandfather died young - he was 48 and my Dad was only 12 - but she was good with keeping up with my grandfather's family. It was a big Irish family, he was the eldest boy of 11 siblings, and so I knew the majority of my great aunts -
the boys in that family all died young. My Dad was also good with keeping up - so I knew - and still know - many of his first cousins and their kids - second cousins, my generation. I even met a third cousin once...
But it sounds like a wonderful tool if you're looking for family. I had never thought of that before. I know that several of my second cousins are interested in genealogy, too - they have researched the Irish branch and even met some relatives still in Ireland. Maybe I'll run across them since they might well have participated there, too.
And I'm planning to get my brother on board after I see how it turns out for me. He may not be interested, but he's all I've got for a sibling, though I could probably get some of my cousins interested, too. As for my aunts and uncles, I've lost all my parents' siblings at this point. I have two remaining aunts, but they were married to my father's two brothers, my Dad was the eldest boy.
And I have checked out the forum just recently looking to see if anyone had posted about these genealogy tests. I know there were posts about it awhile back, but I just got involved myself.