One question that commonly gets asked, especially on the IMDB boads, is wouldn't George and Lorraine notice that their son looks like the mysterious Calvin Marty Klein?

My theory on this is kind of borderline, for one very simple reason: Grandpa William McFly!!

I've always imagined Arthur McFly as looking more like Crispin Glover, rather than Michael J Fox - or else, George's reaction towards Marty Klein might be a bit different.

I think it could very well be conceivable that, a few days after "Marty Klein" leaves town, George might look through some old photo albums. As a result, he might see some pictures of a young William McFly - and realize that he looks just like Marty Klein.

Okay, so if we don't take William into consideration, then would George and Lorraine notice? Of course, part of it would depend on there were ever any pictures taken of Marty Klein - and there's even a reference made to that in the very first draft.

I myself am not very good at remembering faces - so, on one hand, I can see where George and Lorraine would never make the connection between Marty Klein and their son. On the other hand, though, he did play a very important role in getting George and Lorraine together - even though Biff was the one who caused George to really break out of his shell.

So who was Marty named after? Well, I'm sure he was named after Seamus' brother in all the timelines - but, in the improved timeline, they may have also had the added inspiration of the mysterious Marty Klein from thirty years ago.

On a related note, it does seem implied in the first movie that Marty was intended to take after his mother's side of the family - and also that his name was Lorraine's idea. Yet, what we see in Part Three, seems to really contradict both.

Also, come to think of it, that fact really could work in the favour of people who do believe both George and Lorraine are descended from Seamus and Maggie. I myself don't believe that, but it's just something that I thought about.

I don't think George and Lorraine remember exactly what Calvin Marty Klein looked like.

I think Marty was named after Seamus' brother.

Actually, even though I'm sure Seamus' brother would be primary influence behind naming their son Marty - I think they might've also thought of "Marty Klein".

After Marty leaving to change and meet Doc, I can imagine this exchange taking place:

Lorraine: Marty, such a nice name.

George: Yeah, it sure is. Actually, Lorraine, I did have an ancestor named Martin. Well, he wasn't quite a direct ancestor. He was a brother of my great-grandfather, Seamus.

It's true they maybe wouldn't remember exactly what Marty Klein looked like - but I can imagine George looking through old photo albums a few days after Marty left (when Marty's appearance is still fresh on his mind). Then he'd probably go, "Wow! This Marty Klein looks so much like Grandpa William did, when he was young."

Now, flash forward to 30 years, I can imagine George going, "You know, honey, our youngest kid looks a lot like Grandpa William." Then, as an after thought, he might add, "Come to think of it, I remember that Marty Klein also looked a lot like Grandpa William."

Now, of course, there's no reason why they have to mention it on the morning that Marty wakes upo from returning from 1955 - but I'm just saying, with Grandpa William, I don't think George would ever completely forget what "Marty Klein" looked like.