Centuries back and even now, the mother’s maiden surname was used as a child’s first name. Though sometimes they used a grandmother or great grandmother’s surname if it had special meaning or was well know. That’s how there came to be several generations of men named Dummer Sewall. Yes, Dummer, I think it was a maternal great great grandmother’s maiden name, if I remember correctly.
There are some well-known cases of first names that started as surnames: Jefferson Davis, Franklin Pierce, Franklin D. Roosevelt.
On FNC this morning one of the programs had a Tobin Smith (a regular on that show). I wonder if Tobin is a family name. If your last name is Smith there may be an incentive to find an uncommon first name for your kid.
I'm one of those. My mother's maiden name was Mackenzie, and my full name is Daniel Mackenzie Ryan.