cold sore questions, am I immune???

Super weird topic, but I've always wondered if I was immune or just stupid lucky to never get a cold sore. When I was growing up my mom constantly got cold sores, off of the smallest things. If it was too cold out she'd instantly get one. As expected me being little, I'd always be extremely close to her and touching her face and all that kid stuff. I never once got one, ever. I've accidentally shared chapstick or drinks with friends who's had cold sores (forgetting they had one) and still go this day never got one? Which is weird because I know that they're so contagious! So wtf? Have I just been getting lucky or we're they always at a point of being non contagious at the times? Which would be impossible because aren't they not contagious once they're FULLY gone? Scan and all?