Lance Sweets and Daisy Wick kept bumping into each other which resulted with Daisy's pregnancy with their child. In the first episode of season 10, Sweets was murdered by Kenneth Emory. This unfortunate event left Seeley without a father and Daisy to raise him on her own.
Daisy gives birth to him in the episode "The Puzzler in the Pit" as she is surrounded by her friends and family in the hospital room. He is named after both Booth and Sweets.