I don't think one can ever be certain. My siblings are fine but my Dad was bipolar. I strongly believe there is a biological component to anxiety no question. Some folks are just not susceptible to it, others can get it via traumatic experience(PTSD) and others will develop it as they get older and start to take on more in life. That's why I think it's so common in young adulthood for it to manifest itself. Also folks respond differently to therapy. It helps most all, some profoundly, others marginally.