Thread:GreysMedSurgFan/@comment-4287993-20170910094511/@comment-4287993-20170910100043

I don't think that's unimaginable. I doubt they have lots of grandfathers as patients so "grandpa" would be descriptive enough.

Also, he mentioned later in the episode that he and Mark talked about doing a reconstruction so the man in question became their patient before Flight. If Jackson's own grandfather got injured to the point where something needed reconstruction, I think it would have been shown or at least mentioned.