Seeing the child in the adult. Or vice versa.

Expanding on a theme first popularized by ZeFrank in his "Young Me Now Me" series, photographer Irina Werning's "Back to the Future" project creates photos of people that show remarkable correlation with images from several decades earlier. 

The right photos in the pairs above were taken 54, 27, and 33 years after their left counterparts.  Twenty more examples at the link.