Daddy Dearest! Sean Penn Begins Paperwork To Adopt Charlize Theron’s Son

What breakup rumors? Just weeks after reports surfaced claiming Sean Penn and Charlize Theron were breaking up, RadarOnline.com has learned that the engaged couple is back on solid ground. In fact, insiders tell RadarOnline.com, Penn has already begun the process to formally adopt her son, Jackson!

The A-list couple became engaged in November, and Sean "has already begun the paperwork to formally adopt Jackson,” an insider told RadarOnline.com. "Charlize never placed any pressure on Sean to adopt Jackson. It has been a very natural process of them becoming a true family."

"Jackson calls Sean 'daddy,' and Sean just lights up around him,” the source continued. "Sean picks Jackson up from nursery school, and all of the parents know him."

Penn, 54, and Theron, 39, began dating a year ago, and gradually have taken things up a notch as time has passed. An insider told RadarOnline.com back in February that “the two began talking about marriage,” after Theron closely watched how well Penn interacted with Jackson.

The Milk star was previously wed to Madonna from 1985 to 1989, and actress Robin Wright from 1996 to 2010. Theron was previously in a long-term relationship with actor Stuart Townsend.

"For the longest time, Charlize thought it was just going to be her and Jackson, and she was ok with that. There could be a sibling for Jackson in the future as Sean and Charlize have talked about adding to the family," the insider added.