For the first 16 years of her life, Amanda says she thought she knew who her father was. Then, she says, results from a DNA test showed, “He was my brother’s dad, but not my dad.”

TELL DR. PHIL YOUR STORY: Have a story Dr. Phil won't believe?

Amanda says she spent the next 28 years believing another man was her father until a second DNA test revealed she had a half-sister, named Elizabeth, who was not that man’s child. Amanda says that’s when she joined a social media group that eventually led her to David, the man who fathered them both.

WATCH: Dad Says He Wants ‘A Starting Place’ To Rebuild Relationships With 4 Adult Daughters

“He’ll text me every day for a month, and then I won’t hear from him for three weeks,” says Amanda, describing her interactions with David as “very inconsistent.”

Watch the video above to find out what else Amanda discovered through DNA testing, then check your local listing to see where you can watch Thursday’s Dr. Phil.

TELL DR. PHIL YOUR STORY: At odds with a family member?