when you start you may start as a 
a local= someone who has been in the area their whole life and has no knowledge of the horrors outside but is well versed in the local area and its population. downside to this is that you where not ready for something to happen and have nothing in abundance besides household implements (I.E knifes,clothing cooking supplies ect.)
a refugee= someone who has no knowledge of the area but has fought hard and know what they face. they have a bug out bag as well as what ever weapon they had readily available when they evacuated 
both sides have their ups and downs but depending on your cunning and ingenuity you can easily bridge the gap between the two 

choosing your own back story is encouraged and will determine your skill set but i will not allow something ridiculous (i.e cyborg, super solder, werewolf ect) 
also depending on your skills there will be disabilitys and other things that will keep you from being over powered (i.e. heart problems, bad knees, breathing problems ect)