I’ve seen speculation and theories on this particular scene from early in the Jaya arc, when a ship from the sky falls into the ocean and Luffy, Zoro, and Sanji put on makeshift scuba gear to investigate. Luffy breaks things, Zoro gets a friend, and Sanji finds an interesting photo (before collecting rare seashells for Nami):
(Also here’s Zoro and his friend)
Anyway, Sanji has an odd reaction to the photo of the woman. But even though she does resemble his mother…
Especially with the ringlets, and not to mention the ship is from the North Blue according to Robin… but it has to be a coincidence (plus the women in OP nowadays have same-face same-body syndrome goin’ on). The ship itself, and therefore the photograph, was doomed to sail the open White Sea 208 years ago.
Basically, Sanji probably reacted that way to the photo because the woman resembled his mother, and nothing more.
I’d just like to remind everyone that it is Athelstan he is looking at like that whilst asking him to come have sex. If you have a problem with the romantic/sexual pairing of these two men, then I would suggest you take that up with the show’s creators, because THIS is canon.