My e-mail is taken?
I wanted to change the current e-mail in my profile (my mother's) to mine. When I tried, it said my e-mail was already taken. I do not have multiple accounts on this site.
I don't know what your e-mail address is but Duolingo does not check e-mail addresses so it could be that someone has 'borrowed' it either by accident or on purpose.
NB Yesterday I created a new account with a completely fictitious e-mail address just to prove that it can be done.
Check with your sister to see if it's her account first. If so, she should be able to go to Settings and then Deactivate the account. Hopefully, that will clear the e-mail address up for you. If not, then send a note to Support to see if they can help you since your e-mail address is hacked.
remoonline--that's an excellent suggestion. Have some lingots!
Monocerotis, please give remoonline's suggestion a try, but change the password for your e-mail account first so the hacker won't be able to access your e-mail account any more (if they have at all and not just duplicated your address). After you receive the password for the duolingo account, log into it, go to Settings and you can deactivate your old account. Once it's done, then you should be able to go back into Settings in your account and change from your mom's e-mail address to your own.