Anything will seal if you pack it hot and let it cool. But most things can kill you if you 'can' them that way. A seal does not mean the food is safe to eat.
Your ancestors may have been lucky, or the recipe may be one that is ok to do that way. It depends, IIUC, on the ratio of vinegar, peppers, and tomatoes.
You can post the exact recipe and get safety advice from professionals on Gardenweb's 'Harvest' forum. They are very nice, and it's not one of those places where they say everything is unsafe :). If it's ok, they will tell you so!