- She is the daughter of singer/actress Jane Birkin and film director Jacques Doillon. Her half-sisters are actress Charlotte Gainsbourg and photographer Kate Barry.
- She has a son Marlowe Jack Tiger Mitchell (born in 2002).
- She is also an actress. She appeared in 'Kung fu master', 'Trop peu d’amour', 'Blanche', 'Summer Things', 'Saint Ange', 'Sisters' and Boxes'.
- Lou has several tattoos: "Sam's" on her left wrist, one under her left breast, a salamander on her lower back and "Marlowe" on her right forearm.
- She designed a line of clothing alongside her mother for La Redoute.
- She appeared in the 2007 Pirelli Calendar.
