Note: This theory does not apply to the comic universe.I never really thought about it, but recently, the question came to mind "Why does he have two tails?"Well, I have a theory.Dr. Robotnik had been polluting the land for who knows how long. Seeing as Tails was only 8 at the time of Sonic 2, there is a possibility that Tails' two tails is a result of Robotniks Pollution.Now I know what you're saying."But didn't Robotnik just start polluting during Sonic 1?"Actually, no, there is no solid evidence stating that Robotnik had only been a threat for a short while. He could have been dictator for all we know before someone finally decided to take action (Sonic.)Maybe Tails' parents had some tragic accident occur to them before Tails' birth, maybe falling into a batch of radioactive waste or something.The effects of Robotniks pollution had taken effect on a newborns life. This newborn had two tails, and was made fun of for his mutation for his whole life, until the oppertunity came to were he could actually prove himself. He became well known, and was no longer ashamed of his mutation. Robotniks curse on Tails turned out to be a curse on Robotnik instead.What do you think?(Sorry, I'm still tired. Ignore my sleep rambling.)

Tails is a Kitsune which is a Japanese Fox legend. Think Naruto and the Nine Tails. That's why he has two-tails because Kitsune's have more than one tail. 

That definitely sounds like it could be right Unfortunately, we'll never know for sure but that's interesting.

Note: This theory does not apply to the comic universe.I never really thought about it, but recently, the question came to mind "Why does he have two tails?"Well, I have a theory.Dr. Robotnik had been polluting the land for who knows how long. Seeing as Tails was only 8 at the time of Sonic 2, there is a possibility that Tails' two tails is a result of Robotniks Pollution.Now I know what you're saying."But didn't Robotnik just start polluting during Sonic 1?"Actually, no, there is no solid evidence stating that Robotnik had only been a threat for a short while. He could have been dictator for all we know before someone finally decided to take action (Sonic.)Maybe Tails' parents had some tragic accident occur to them before Tails' birth, maybe falling into a batch of radioactive waste or something.The effects of Robotniks pollution had taken effect on a newborns life. This newborn had two tails, and was made fun of for his mutation for his whole life, until the oppertunity came to were he could actually prove himself. He became well known, and was no longer ashamed of his mutation. Robotniks curse on Tails turned out to be a curse on Robotnik instead.What do you think?(Sorry, I'm still tired. Ignore my sleep rambling.)

That's quite a theory you have there, Antoine. But I doubt it has something to do with my parent's had some kind of tradegy. But then again, I do wonder why i have never seen my parents before and how I am an orphaned fox.