Season 4 | Episode 15 | Aired 05/11/08
Katherine tries to warn Dylan about Wayne, but Dylan continues to see her father anyway. Katherine tells Wayne that she got revenge for his abuse during their marriage by having several affairs and that Dylan isn't even his. He takes some gum Dylan was chewing and submits it for a DNA test and is horrified to find that Katherine was telling the truth.
He gets drunk and watches a home video of Dylan as a little girl, after she'd bravely gotten several stitches on her arm. He calls her and asks her to come over: He's got some things to tell her about her mother. When she arrives, he starts examining her arms and then angrily orders her to leave, although he won't say why.