"I felt like the world was coming full circle."

Its not unusual for your sister to attend your college graduation, unless you never knew you had a sister. That's what happened at Columbia University this month. The story began years ago, when Leslie Parker, 54, gave birth to two daughters as an unwed teenager in Florida. Leslie aspired to be a writer, but drug abuse, poverty and emotional problems dashed her hopes and caused her to give up both girls for adoption. "If I had raised them, they would not have had the privileges they had," she said. The two daughters, Lizzie Valverde, 35, and Katy Olson, 34, didn't know each other when both enrolled at Columbia in 2013. They met, of all places, in a creative writing class.

Katy Olson and Lizzie Valverde were given up for adoption.

On the first day of class students introduced themselves, and after class, Katie, who knew she was adopted and had a missing sister, approached Lizzie very excited, asking a lot of personal questions. Lizzie thought Katy was having a panic attack until Katy exclaimed, "I think we're sisters!" She was right. Until that moment, Lizzie didn't know she had a sister, but she had discovered their birth mother through online research and met her. She encouraged Katy to meet her too. But when?

This month, Lizzie graduated with a B.A. in creative writing. Katy, who graduated last year with the same degree and is now pursuing a master's degree in writing at Columbia, was there to congratulate her. Their birth mom also attended, meeting Katy for the first time.

"In them I see what I had the potential to be," Parker said. "They're both living what I always wanted to be. I felt like the world was coming full circle."