All I can say is you have a predisposition to it—it’s a neurological glitch. But stuttering is easily affected by stress. So you already had a predisposition to stutter and when you were at the age to speak sentences—in your case around 5 years—you began. Your grandfathers death may or may not have been related but occurred at about the time you would have started to stutter anyway. The stress or upset may have triggered the stutter. There are highly complex neurological reasons theorized for stuttering. The thing to realize is it’s not because you’re crazy or nervous. The stuttering comes first. The anxiety occurs next—embarrassment around stuttering—which then, unfortunately makes it much worse. The approach-avoidance conflict becomes the greatest obstacle. When a person wants to speak, but at the same time hesitates or is anxious about speaking the worst stuttering occurs. If they can learn to allow themselves to stutter they can be fluent or “stutter fluently” as the do speaking to themselves or a pet.