I've had the same problem online for years, when I translate something people presume I am using Google Translate (even though in one case said language isn't on Google Translate — I checked!)... Or got the answer off Wikipedia.
One of the funniest things was being accused of plagiarising Wikipedia, when I'd actually written most of the Wikipedia article on said subject. The irony... Wikipedia doesn't just use unpaid labour, it ends up undermining the people who wrote it.
> when I'd actually written most of the Wikipedia article on said subject. The irony... Wikipedia doesn't just use unpaid labour, it ends up undermining the people who wrote it.
Surely it would be relatively easy to offer to show the edit history to prove that you actually contributed to the article? And, by doing so, would flip the situation in your favour by demonstrating your expertise?
The fact that you should have to is pretty annoying but also fairly edge case. And if a teacher or institute refuses to review that evidence then I don't think the credential on the table worth the paper it's printed on anyway.
One of the funniest things was being accused of plagiarising Wikipedia, when I'd actually written most of the Wikipedia article on said subject. The irony... Wikipedia doesn't just use unpaid labour, it ends up undermining the people who wrote it.