I have a 645 credit score, do i need a co-signer for a home loan?

I make about 45k a year, I have no more debt but the damage is done. Im not looking for a big home about 155-160. My parents have good credit and are willing to help but they have a mortgage of there own. Can they still co-sign? and if they can, can they be removed for the loan in a couple years?