@Rex: Based on Alma Torran's History, all of whose blood is human has the magician genes in them. People were once mistreated by other stronger creatures, predating them, eating them, torturing them. That is why Il Ilah granted the Divine Staves (par with the metal vessels in the New World) to the human so that they can rule the Old World, whatever the race is. But blinded by vengeance and hatred, the people from the Orthodox--an organization of magicians, used the staves to control the creatures that once hurt them, turning them into "monsters" they've never been before while holding their brains to work for them. Alas, Solomon, who was once a magician working for the church, realized what he was doing was wrong, so he decided to retrieve all the staves so that he can achieve world peace.

He had all 72 together, and ruled Alma Torran for the serenity. But Al Thamen--the Orthodox that once--decided a new way to bring back their Father, Il Ilah to the world to punish all those who didn't follow His orders, and against them, King Solomon sent all his households--the seventy-two people who hold the Divine Staves, transformed into Djinns and fight the medium of the God. They were defeated, however, and Solomon decided to use his magic to create a New World where the new king to replace him will be born, and be chosen by the magis.

That being said, Djinns are once humans also, so yes, they all have different skills, wisdom, and other things. I will specify some that were already said in the anime/manga, but for others, I guess you would want a little creativity with that, eh? :D

@Jay: Could you elaborate more on the background part wherein all of those abilities would be appropriate for his profile? I guess Marid needs that.
[s]and oh my Shizuka doesn't even have a complete background yet. shame on me -.-[/s]