Bobby Neel Adams - Couples
Bobby Neel Adams is a New York-based artist whose "photographic work addresses the transformation of the human body by aging and circumstance." His series "Family Tree" involves combing photos of parents with their children, using re-sizing and manually placing the photos together to show the two people as one. Adams is clear that no Photoshop is used in the project.
He used the same technique for his project "Couples". You can see more of his work at bobbyneeladams.com.