Crits & stuff happens.My rule is don't write a backstory so long that if, in the first session, a goblin rolls boxcars on a critical hit when you're at 1 hp, you get mad and quit the game.
That's fine, I'll tell you all about it verbally.Personally, I’m not going to read a player backstory that is longer than a paragraph or two.

I love a backstory because it shows that the player is engaged.
In my experience a starting character needs to answer at least the following questions:
1. Where are you from (pick a town / village or region form the map)
2. Why did you leave home? (what made you give up your old life for one of adventure)
3. Who are you leaving behind? (a family, a love, a bad reputation, an arch nemesis)
4. What are you searching for? (adventure, riches, the lost wand of take that you fiend)
This gives me enough to inject some of your backstory into the plot of the game.
I must admit that I have railroaded the GM on one occassion in almost 40 years. A husband and wife team were running a game of werewolf and sadly hadn't done their homework. A fellow player and I took copious notes early on in the game and essentially started driving the plot by correcting the GMs when they had forgotten what direction the game was supposed to be going in. It ended up being a great game that the players were all really engaged in and the GMs walked away really proud of how it had all gone down. If it's done with kindness and in the right spirit it can work sometimes.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.