I’m pretty convinced Zoro is of the Shimotsuki clan, or at least diaspora of Ringo, Wano.
Chapter 953 revealed to us the existence of the Ringo region in Wano; as well as it’s Daimyo, Shimotsuki Ushimaru. Ushimaru was killed after refusing to obey the new Shogun, Orochi after he had executed Lord Oden 20 years ago. As a result he lost his life.
Zoro is currently 21, so if he had been in Ringo at the time, would have been around 1 years old. For the survival of the family, he would’ve been shipped to safety out of Wano to the East Blue, al-la-Kakarot out of Planet Vegeta.
Supporting Evidence
1. Zoro and Shimotsuki Ryuma look alike, too alike. They also both look like the silhouette of Shimotsuki Ushimaru.
Pretty straightforward observation. They all have the same bloody hairline.
2. Ushimaru Shimotsuki and Shimotsuki Ryuma are from the same clan.
We never got Sanji’s family name until we learned he was a Vinsmoke. Wouldn’t be surprised if it’s the same rule with Zoro… Roronoa Zoro Shimotsuki? Shimotsuki Zoro Roronoa? Roronoa alias is finished?
3. Shimotsuki Ryuma’s grave was robbed for his body AND Shusui, almost confirming he had an eternal grave in Ringo. His body froze, and didn’t rot, and his blade was still with him.
In chapter 953 it was explained that the region of Ringo is so cold that corpses don’t rot, their bodies only freeze; and that they bury them with their swords, given to them at birth, so they can use them in the afterlife.
Given that he is ancient, Ryuma’s corpse and weapon being used by Moriah in Thriller Bark alludes to the fact that they were both available due to having an eternal grave. If so, Ryuma was probably buried in Ringo.
4. It (fate) so happens that Zoro is the one to return to that land of Ringo, and he was also the one to rightfully take Shusui off Ryuma.
5. A ship left Wano for the East Blue a few decades ago.
Oda speaking about some people I can’t care to remember…“They actually aren’t the same person! They have the same last name because they’re related by blood. The fact of the matter is, a ship from Wano reached East Blue a few decades ago,”
“One of the descendants of someone on that ship is a person that everybody is familiar with,” he revealed. “This part might be featured later in the main story so I won’t mention any more than that. It isn’t going to be a major plot line, it will just be a minor story.”
Oda of course playing it down, in case it is a major plot line.
6. Zoro hails from Shimotsuki Village in the East Blue – where he plied his trade in swordsmanship.
7. Shimotsuki is the traditional name of the month of November in the Japanese calendar and a Japanese surname. Zoro is born November 11th.
*Theory by Nirex