Greg O'Brien

Greg O'Brien is the father of Sarah O'Brien, who was switched with Emily Stinson as an infant.

History
Greg and Beth O'Brien had a nine month old, Emily, who had been ill since she was an infant. Cooper was concerned because Greg didn't seem to have bonded with Emily at all and seemed disinterested in her care. The cause of her neurological symptoms was a mystery until a blood draw showed Pelizaeus-Merzbacher disease, an incurable genetic disorder. Concerned about it being genetic, the O'Briens requested tests to figure out which of them had the genetic marker. When tests revealed that neither of them was a carrier, the doctors concluded that Emily wasn't their daughter. Greg and Beth were told that under California law, they'd have to say goodbye to Emily and welcome the other child into their home. Beth insisted that it couldn't be true, believing that as a mother, she would know. After obtaining the nursery records, they determined that their baby had been switched shortly after birth with Duncan and Melinda Stinson's baby.

Duncan was arrested after it was discovered that he had switched the girls in the nursery after Emily had a seizure while he was holding her. Under the observation of Violet Turner, the O'Briens handed Emily over to Melinda and took Sarah from her. Cooper noticed Greg crying to the side and Greg told him that he thought he couldn't watch Emily die and now he was having trouble saying goodbye to her.

Romantic
He is married to Beth O'Brien.

Familial
Greg and Beth have one child. They named her Emily at birth, but after she was switched, she was called Sarah. When they were nine months old, the girls were switched back to live with their birth parents. They spent nine months raising the Stinsons' baby, who had an incurable genetic disorder.