Isn

The days leading up to a toddler's second birthday are seen alternately from the child's point of view as well as that of his parents.

Boy meets girl; boy falls in love (and had wild, non-stop sex) with girl; boy loses girl... when they discover they are brother and sister! But when he learns that he's the victim of the ultimate case of mistaken identity, the lovesick young man -- whom everyone still thinks is after some taboo thrills -- must race across the country to stop her from marrying another man.

A medical documentary for students.