Subjects in an experiment were shown pictures of people of the opposite sex and were asked to rate their attractiveness.  Some subjects were first subliminally flashed pictures of their opposite-sex parent.  For other subjects the pictures they were rating were actually a composite image made from pictures of the subject himself.  Both of these induced higher attractiveness ratings.

Finally, in a third treatment the subjects were falsely (!) told that the images they were seeing were partly morphed from pictures of themselves.  This reduced the attractiveness ratings.

Here is a link to the paper.