Here are a couple of problems that I have with photographic comparisons:
* It's always easy to spot a resemblance between similar physical types. There was a girl in my college sorority called Laura who bore a strong, strong resemblance to GD Marie in terms of build and general facial characteristics. When Laura reaches middle age, I have no doubt that photos of her would echo this resemblance, and give us an idea what Marie might have looked like had she lived that long. And I don't suppose that Laura is the only person ever born to look like Marie -- there must be, after all, a certain finite number of ways that facial features can be arranged, as well as a finite number of physical types. I find it easy to write off photographic comparisons for this reason alone, especially as --
* -- most comparisons that we are asked to make are between a photograph of a young Grand Duchess and a middle-aged or even elderly woman. Are there NO photos of these claimants at a young age? For instance, a photo of Olga and Michael at the time of their wedding might be nice.
* I think our minds are pre-conditioned by our own prejudices to reject or accept these alleged resemblances -- in other words, if you want to see the likeness, it's there, and if you don't, it's not. I think professional photographic comparisons are more complex that just eyeballing grainy photos.