Generation shifting

I got this image in email this morning, from my mother. Taken fifty-four years ago, it shows (from left) my great-grandfather, my father, and my grandfather, three men with the same name.
What's striking to me is not how much my father looks like I did when I was little, but how much my grandfather—twenty-nine at the time, if my math is right—looks like I do now. Except older. I think only my family would see the resemblance, the shape of the head and nose, the way his eyes are set, the ever-present ears, but to me it leaps out like I'm looking at a mirror.
Everything has changed about the setting of the picture, too. None of the structures pictured still exist, the gravel drive is paved, part of the yard overgrown, trees fallen and replaced. But I recognized that, too, immediately, as if the very contours of the island (yes, it's on an island) are printed in my DNA.
The thing that's startling about recognizing my own face in my grandfather's is how far apart we are. At twenty-nine, he had two children, lived almost half his life, and was set in the path that took him to becoming the man I knew. The details of the world we live in have changed remarkably—I don't think I could explain to him what I do in a way that he would understand—but we're so close to being the same person. It's as though I'm living his life with different decisions, to see how it might have been different. I wonder how I'm doing, in that perspective. I wonder if I'll ever know.
Looking at it more, another striking thing about the image is how much my father looked like his granddaughters. Or vice versa.