If you're trying to trace a Swiss relative, the starting point is not necessarily where he was born, but the town/village where his family holds citizenship (also called his place of origin) - roughly speaking, this is usually the place where the family was first recorded. Children automatically take their father's citizenship, and when a woman marries, she loses hers father's citizenship and acquires that of her husband. (Ths has become a little more flexible recently!) Vital records for each family dating back to the start of civil registration are held at the town/village where they have citizenship - this date varies from canton to canton, but is generally the early 1800s.
So - how can you find out where someone held citizenship?
1. Passport
2. Livret de Famille/Familienbüchlein
3. The Swiss Surname Register
1. Passport
Self-explanatory! If you're lucky enough to have g-grandad's passport, look for the words "Heimatort"/"Lieu d'origine"/"Luogo di attinenza" or similar.
2. Livret de Famille/Familienbüchlein
If your relative was married before he left Switzerland, or if he immigrated with his parents, somone in the family may have a small hardcover booklet (like a large passport) with the family's details. The first entry will be the marriage details, and will include the place(s) of origin as above.
3. The Swiss Surname Register
Also called the Swiss Surname Book, this is published in English under the title "Swiss Surnames: a Complete Register" by Picton Press, and lists the place of origin (citizenship) for all Swiss families. I believe it is currently out of print, but your local library should be able to get hold of it for you. (NOTE - Sorry, but I don't have access to a copy!)
Once you know the place of origin, you can contact the appropriate register office - some are more helpful than others, but you will probably need to supply some kind of proof that you are related, and there may be an administrative fee, so it's worth checking first.
Rambler