Until now, Ben Affleck has been outnumbered at home, once joking: "I have three women in the house. … I get to be wrong three times a day".
But now the actor finally has an ally after his wife Jennifer Garner gave birth to a little boy.
The new arrival will be a playmate for big sisters Violet, six, and three-year-old Seraphina.
The child's name has not yet been announced, but a source confirmed that Jennifer had welcomed her son in Santa Monica.
Soon after the couple announced the pregnancy in August, reports emerged that the actress was expecting a boy.
While Ben, a huge fan of the Boston Red Sox baseball team, was excited at the prospect of having a son to play ball with, Jennifer admitted she was more apprehensive.
"She feels like she won't know what to do. She's close to her two sisters, and her instincts were spot-on with the girls" a friend said.
Jennifer herself admitted on the Ellen DeGeneres Show that it would be "so weird to have a boy" but also said it would be "cool and different."