Ah, internet rumors. At JONJ we deal with them every day. Once you see someone claim that Kevin Costner is Jewish, you've seen them all.
Well, there are no Jewish rumors about Jamie Lee Curtis. She is, through her father, Tony Curtis (born Bernard Schwartz), a famed actor in his own right.
The rumors about Jamie Lee is that she's a... hermaphrodite. Has male and female body parts. Yeah, that one might be a tad harder to prove than if someone is Jewish.
The sources of the rumors? Her asexual name, her asexual haircut, and her adopted, as opposed to biological, children. (As if!)
Yes, seems flimsy. But snopes.com, the website that issues verdicts on rumors, call this one... undetermined.
Perhaps someone should start HermaphroditeOrNotHermaphrodite.com...