The only character history I'm interested in getting from my players at the beginning of a game is something which can be summarised in a few sentences.
For instance, from my Eberron Savage Tide group:
A is playing Diegur, a human fighter who was born into House Orien but didn't possess his father's sorcerous talents or the dragonmark of the house. When his younger brother Lutagnan did manifest both, and their parents began to neglect their eldest son in his favour, Diegur decided to leave home before he began to resent his family too much. He subsequently became a mercenary, and his last job left him looking for work in Sasserine.
G is playing Lutagnan, Diegur's favoured younger brother, a human sorcerer with the Least Mark of Passage. Because their parents spoiled him, Lutagnan never really learned a sense of responsibility; when Diegur left home to adventure as a mercenary, Lutagnan thought that sounded like an interesting life too. He discovered his brother was heading to Sasserine and followed him there, oblivious to his brother's reasons for leaving and their parents' distress at his abandoning his responsibility to the family.
N is playing Silk, a warforged rogue. Silk was discovered, damaged and severely amnesiac, by the parents of Diegur and Lutagnan when the brothers were young, and was taken in and trained as their bodyguard and manservant. He's been sent along with Lutagnan by the brothers' parents to keep him safe until he tires of adventuring and comes home to his responsibilities.
E is playing Alth, a gnome druid. His parents' ship was scuttled by slavers when he was very young, and he grew up as a slave to one of the noble families of Sasserine. An instinctive kinship with the earth and the vermin which burrow within it led him to the druid's path. After he was eventually freed with the connivance of his cruel master's more compassionate children, he's begun seeking a way out of Sasserine.
L (my wife) is playing Mike, a changeling artificer masquerading as an unmarked member of House Cannith. She was raised in Cyre and trained by House Cannith, and since the Day of Mourning she's decided it's easier to pretend she belongs to the house - it's hard to prove "Michaela Cannith" never existed. She's in Sasserine precisely because the dragonmarked houses have very little presence there, however.
M is playing "the Marcher", a ritually-nameless apprentice shaman from a tribe of the Shadow Marches. He's been sent into the world on the trail of certain visions and prophecies both he and his mentor experienced, and receives flashes of insight into the nature or destiny of those people he meets who will be important to his own future - which is the reason he ended up travelling to Sasserine on the same ship as Lutagnan and Silk.
There was genuinely not much more to these characters' backstories than what I've written here, though I've worked with each player to develop their ties to the setting since then - clarifying their attitudes towards certain elements of the world, that sort of thing.
