Its not really mentioned in the other games that I can remember and is not explained yet in detail in game (I am sure it will be much more prevalent later).
Anyway spoilers from the first act.......
If you notice the place you get bless skill you are talking to a former god and they kind of...... choose you to succeed them I guess? I think in that act you become a godwoken and you have the potential to become a god. Pretty sure some of the seekers explain it in their own way but I cant remember what they said.
As for whats happened in between..... pretty sure the divine divinity game happened but its not totally lining up with the game plot, the story itself feels pretty much not linked well with the other games imo. Its more standalone than sequel.
Though as to exactly what has happened try this link
http://divinity.wikia.com/wiki/Timeline
