Where'd Brad Pitt, Angelina Jolie get those baby names?

Unusual celebrity baby names are in the news again with this weekend's birth of Angelina Jolie and Brad Pitt's twins.

Not Isla Marcheline and Amelie Jane, as had been initially and erroneously reported a few weeks ago.

Instead, Angelina and Brad named their new son and daughter Knox Leon and Vivienne Marcheline.

Some readers have been wondering where they got those names. According to "The Baby Name Bible" author Linda Rosenkrantz, interviewed at People.com:

1. Shaking the Family Tree: Knox is a Scottish-English-Irish surname and the middle name of Brad's grandfather, Hal Knox Hillhouse. Léon is the name of Angelina's great-great grandfather.

2. The X-Factor: The Jolie-Pitts' two other sons, Maddox and Pax, have an x in their first names.

3. Mother Complex: Vivienne is the French form of Vivian, which may reflect her birthplace or heritage. Or it could be a name in Pitt's family, because their baby boy is named for people from both parents' families. Marcheline is the French name of Angelina Jolie's late mother, who was of French-Canadian and Native American ancestry.