Watch Sibling Seductions 4 Full Movie Free Online 123Movies. Lacy is making a documentary about step siblings who are romantically involved after she discovered a compilation of stories online about siblings hooking up. She reached out to a few of the writers who agreed to tell their stories over video. But, through the course of listening to their stories, something strange happened. Not only did she start to believe their stories, she began to understand why they were so attracted to their stepbrothers. She went from being amazed by the erotic tales they confessed to her, to masturbating to the raw interview footage. Soon she was reconsidering her relationship with her own stepbrother, Tyler. Before she can finish her film, Tyler discovers the raw footage. He confronts her and asks if she is interested in the topic from a purely academic point of view or for far more personal reasons.