By Wendy Widom

CHICAGO (CBS) — People who say you can’t pick your family may change their mind after learning about teen Lauren Hernandez of Plainfield, Illinois.

This past weekend, Lauren presented her mom’s boyfriend with a very special gift to make their father-daughter relationship official.

Lauren invited family and close friends to the family’s home for a graduation party. At the celebration, she presented a wrapped box to Joe Iosco, her mom’s boyfriend of 17 years.

Joe opened the box and read a framed poem he found inside. Beneath the poem was a second surprise: adoption papers that would legally make Lauren his daughter.

Joe’s knees gave out as he sank to the ground. Tears flowed from his eyes and Lauren’s eyes. Around the yard, their loved ones cheered as father and daughter hugged.

When asked why she wanted Joe to legally adopt her, Lauren described a man who made her feel completely loved.

“I never doubted that he was my dad. The fact that it’s going to be official makes me happy.”

Lauren says Joe has always made her feel wanted. “He’s been there for everything for me.”

Sally Hernandez, Lauren’s mother, agrees. “When your kids are born, you automatically love them,” she says. “He chose to do for her what he does for his biological daughters.”

Joe tells CBS 2 that he has been in Lauren’s life since she was one year old and loves being a father to her. “I’ve wanted nothing more than to be her dad from Day One.”

Says Joe, “Growing up I came from a separated family. I always had it in my mind that I would never want other kids to go through that.”

As for Lauren’s special gift of adoption papers, Joe says, it is “one of the best things I’ve ever received in my life.”