Boyd Vogelson is the only son of Kristin Baxter and Ryan Vogelson". In Season 1, he was portrayed by either Evan or Luke Kruntchev, both of whom are twins, but is replaced by Flynn Morrison from Season 2 onwards in accordance with the character aging. In Season 7 producers decided to age up the character and replaced him with Jet Jurgansmire. He first appeared in the episode "Last Baby Proofing Standing".
He was two in the first season, his age was advance three years by season two.
Boyd was born when his parents were still in high school. He moved out of the Baxter home and into an apartment with his parents in the third season. He originally went to Wilson Elementary, but was later transferred to Clark, a better option. Later on, in the show, Boyd was pulled out of Clark, and from there on Ryan home schools him.
He is Mike's little shadow and loves to spend time with him and play jokes on his family.