For the folks who didn’t see it in the tags of my earlier post, here’s the canonical origin for “Vernet.”
The Adventure of the Greek Interpreter:
“In your own case,” said I, “from all that you have told me, it seems obvious that your faculty of observation and your peculiar facility for deduction are due to your own systematic training.”
“To some extent,” he answered, thoughtfully. “My ancestors were country squires, who appear to have led much the same life as is natural to their class. But, none the less, my turn that way is in my veins, and may have come with my grandmother, who was the sister of Vernet, the French artist. Art in the blood is liable to take the strangest forms.”
And then if you want a bonus reference that you can choose to interpret as either connected or just the usual ACD name issues…
The Adventure of the Norwood Builder:
At the time of which I speak Holmes had been back for some months, and I, at his request, had sold my practice and returned to share the old quarters in Baker Street. A young doctor, named Verner, had purchased my small Kensington practice, and given with astonishingly little demur the highest price that I ventured to ask—an incident which only explained itself some years later when I found that Verner was a distant relation of Holmes’s, and that it was my friend who had really found the money.
(Doctor Verner was already referenced in The Empty Hearse, though there was no mention of his being related to the Holmes family.)