Some speculate so, yes. And via thorough research it is easy to understand why. Cicero, being a master of disguise, could have potentially fooled the Hero into believing he was a Bosmer child. However, there are some deductions:
Cicero is mad, so I believe if you were to turn down the Adoring Fan, he wouldn't be so patient.
Also, you can potentially just brutally murder the Fan, which means he wouldn't even be alive in the next game.
Last and most importantly, Bosmer, Altmer, Orsimer, Dunmer, Falmer, etc. live much longer than Men. They are not immortal, but live for quite a while. So the Adoring Fan could be alive by the events of Skyrim, but Cicero couldn't be. If I am correct, our beloved Cicero, correct me if I'm wrong, is an Imperial. Which again, correct me if I'm not right, don't live as long. In order for Cicero to be alive during the Oblivion Crisis, he would have to be over two hundred years old by the events of Skyrim. Imperials, being Men, don't live that long.
So, it's a good theory, but it's just implausible. But I could be wrong.
Unless, of course, Cicero is just another alias for something greater...