I can only go on what I've read:
Goal: Back to the slightly colder surroundings that are Merseyside for a moment; is it true you were a boyhood Everton fan? How did that square with playing for the Reds?
RF: When I was very young I used to watch them but I was at Liverpool when I was 11 years old – I’ve been a Liverpool fan from then on. Obviously I grew up watching very, very good Everton sides but I always knew deep down Liverpool were a better team.
Goal: Jamie Carragher mentioned in his autobiography that he left Melwood to join the Everton ranks on a couple of occasions in his teen years. As a boyhood Evertonian, did you ever do the same or feel the urge?
RF: Before I was 14 years old I had a chance to sign for Everton but being at Liverpool, I was quite a loyal lad and because they had raised me I just didn’t want to jump ship. At that time it would have been easier to get into the Everton first team but I stuck to my guns and am happy with decision I made!
http://www.goal.com/en/news/808/australia/2009/03/27/1177288/exclusive-robbie-fowler-interview