Sean Penn files to adopt Charlize Theron's son - report

Sean Penn has filed documents to begin the process of adopting Charlize Theron's son, according to a report.

The actor has been dating the blonde beauty since 2013, and they are rumored to be engaged to marry.

A new report now suggests Penn is taking the relationship to the next level by becoming the legal father of Theron's adopted son, Jackson, three.

A source tells Usmagazine.com that Penn has filed paperwork to begin the process.

The Mystic River star has two grown-up children, Dylan and Hopper, with his ex-wife Robin Wright.