This rather cursed screenshot was sent to us, and we regret to inform you that quite a lot of people seem to believe this myth, and related myths surrounding the vulva. These myths been around for literal millennia, even though there is no rooting whatsoever in reality. Let's take a little look at the history of misogyny and racism inherent in this belief...
A caveat: Throughout history, a lot of written sources have used terminology very inconsistently, to the point that sometimes it's hard to know exactly what the fuck they were talking about. For example, "nympha" was sometimes used to refer to the clitoris, sometimes the labia minora, sometimes both.
However, what is clear is that a hell of a lot of European men since Ancient Greece had some pretty gnarly attitudes about how the appearance of the vulva said something about the character of the person.

The general prevailing belief was that clitorises and larger labia minora were not really something that Nice White Women had. A vulva that wasn't "an innie" (a phrase not used in history) indicated some sort of masculinity - perhaps lesbianism, perhaps promiscuity, perhaps being a bad wife.

Larger labia, to a European physician for a hell of a lot of history, basically indicated that it belonged to a woman who transgressed patriarchy in some way.

There was a hefty degree of racism to this belief too. European physicians and authors believed that larger labia were something that African women had, not Nice White Women.
Saartjie Baartman, a Black Khoisan woman from present-day South Africa was transported to Britain in 1810. She was exhibited in a freak show act under the name "The Hottentot Venus", with great attention drawn to her labia and her buttocks.
So, in short, the myth is misogynistic and racist af. And just in case anyone needs to hear it today:
✨Something as insignificant as a penis cannot possibly change the appearance of the vulva✨
The depressing thing is that this myth isn't just niche, even a quarter of the way through the 21st century. One of our least favourite objects in our collection is a medical textbook outlining the difference between "true" and "false" virgins based on labia shape, size and colour. It was published in 2012. https://www.vaginamuseum.co.uk/muffbusters/2d-textbook
Myths in Textbooks — Vagina Museum

Vagina Museum