I understand your caution and actually your concerns are not without foundation: both chicken pox and shingles are caused by the varicella-zoster virus.
Initially, the virus causes chicken pox, an extremely contagious condition. Even touching the skin of an infected person or putting on a piece of clothing worn by them can pass it on. This is why it is unusual, although not unheard of, for people to reach adulthood without being infected.