A specialized Y-DNA test shows that my genetic group is R-M269. That group is pretty generic but when I search for people who match my specific DNA markers, I find them heavily concentrated in the the British Isles, which makes sense given that our distant Simpson ancestors were Scotch-Irish.
When looking at specific matches for my Simpson chromosome, I found no close relatives. Apparently not many Simpsons do DNA testing. However, it did show very distant cousins where our common ancestor likely lived several centuries ago. Looking at Europe, those distant cousins appears to be mostly in Scotland which, happily, supports the written evidence.