Chicken pox and shingles are the same virus but in different forms. Chicken Pox is usually the first presentation, which typically happens in younger individuals and with a characteristic patten of blisters, crusting and a trunkal rash, while Shingles tends to happen later and can be associated with painful blisters in a nerve distribution.
The varicella virus sits within the nerve endings, after the initial Chicken Pox infection, and if you become unwell or your immune system is under attack, it can develop as a secondary infection. Sometimes with Shingles, you can develop a tingling sensation beforehand or post-infection nerve pain.
For your father, it is likely that he did have Chicken Pox at some stage of his life, but it maybe that it was considered mild or sub-clinical. Sometimes it might be worth seeing a GP or general physician for more advice.
Hope this helps.
BW
Dr Dinesh