As I have said on amother thread I believe that Norman is Ash's fathers. Here are the facts that lead me to believe this:
1. If you look at Ash, May and Max they are both likely to working in the three main areas of pokemon, either training to become a Gym Leader of Pokemon master, breeding pokemon to their best ability or studying pokemon. With Ash you can see that he would be perfect as a Gym leader in around 5 or 6 years, with May she is obviously training for pokemon contests which involves training her pokemon to the best of their ability, like a breeder. Finally with Max he is a expert of pokemon and would probably follow in the footsteps of Gary Oak in terms of starting of as a trainer, collecting badges, but then moving on into the field of studying pokemon. So with Ash, May and Max they all are concerned with the three main areas of pokemon, coincident, I don't think so. Ash is obviously Norman son.
2. It would explain why Norman (if he is Ash's father) never return back to Pallet Town, as after leaving Deliah he travelled around and meet Caroline and married her.
3. If you look at the age difference between Ash and May you could say that it was about 3 or 4 years. If Norman left Deliah when Ash was just born, by the time he had travelled around, met Caroline, married her, and had May it would most likely have been 3 or 4 years. If it took Norman 2 years of travelling, around other places before Houen, then met Caroline and after a year got married, then about a year for May to be born then it would tie in with perfectly from the time Ash's father left. Again another point backing up my theory.
4. If Norman was Ash's father and, like in my previous point he left when Ash was young, it would explain why Ash wouldn't recognise him and visa versa.
5. It would explain where Ash gets his rare abilities from, seeing as Norman is a Gym Leader he does need to be a good trainer.
6. Norman battle strategy is a lot like Ash when he started off, he relys on winning with brut strength and power. This is how Ash used to battle as he also relied on his pokemon using powerful attacks to help him win.
So this is why I think Norman is Ash's father. I could go into more detail with some of my points but you would probably get bored of reading it.