Charlize Theron is getting ready to adopt a second child.

The "Monster" star is keen for her son, Jackson, two, to have a sibling, and will be starting the process in the New Year. "Charlize admits it's a lot to go through, but she definitely wants Jackson to have a little brother. She's starting the process all over again right after the New Year. She wants Jackson to have a sibling who isn't four or five years younger than him - she wants to raise them together," a source said.

The South Africa-born actress has not yet decided which country to adopt the child from or whether he or she will share Jackson's African-American heritage. "She's made no decision about that yet. She is eyeing the possibility of adopting a child from South Africa this time, but she hasn't decided. She just knows she wants another baby," the source added.

Charlize - who split with long term partner Stuart Townsend after nine years together in 2010 - became mother to Jackson in 2012 and claims she always knew she would adopt. "My mother found a letter I wrote. It said, 'Would you please take me to orphanage, so that I can go and adopt a baby?' I always knew I would adopt. Always," she previously said.