The one on the left is Dan Ettinger, by far the best thing about the latest of the Royal Opera House's inexorable La traviata revivals. The one on the right is his erstwhile mentor, The Other Dan.
Remarkable, isn't it?
But it was not always thus. Back in 2009, the then-newly appointed General Music Director of the Nationaltheater Mannheim looked more like this:
UPDATE - Thanks to Simon Morgan for pointing out that Dan E has gone on the record to say he's not Dan B's son.