Just a few months ago I celebrated my 75th birthday with a family reunion on the shores of Lake Chapala, Mexico's largest lake and the site of our winter home. We ranged in age from 13 months to 75 years. Somewhere along the way I had become the senior member of the family - the previous generation had become little more than memories, lost but for a few faded photographs. I wished I knew more about my parents, my grandparents or perhaps my great-grandparents who lived in a pre-industrial world before the advent of cars and airplanes, before telephones and electricity, even before photography...