Does your co-founder have to be the same age as you?
Mz: I would assume that it's a lot like dating:  If the age difference is An Issue between you and someone, then it's a problem and can be a show stopper.  If it's not, it's not.  In some cases, what you have in common in terms of lifestyle, interests and so on can overcome the difference in age.  In other cases, those strengths just aren't there.