ChainsawAsh said:

2 was also when they started casting the same people for different generations of characters - Michael J. Fox plays Marty and Marty's two children, for no good reason. It's distracting, even though the fact that Marty, Jr. looks exactly like his dad is a plot point. It's just a bit ridiculous. Of course, 3 makes this even worse by casting the same actors as their century-prior ancestors - but that's to be expected, since 3 is basically a parody of itself.

You'd be amazed at how the gene pool repeats itself in some family trees. My father had an Uncle that was the spitting image of him, only much older. An old friend of mine once showed me picture of his grandfather from WWII, and I thought he was pranking me. The resemblance was uncanny. Unless he actually went back in time and was part of a bomber crew!

I've had more than enough odd encounters in my life to make me think I have an evil twin out there someplace. ;)