Kylie Kristen Jenner turns 25 years old today. Here are five things you may not have known about the young cosmetics queen. 1. She first starred in 'Keeping Up with the Kardashians' when she was 9 years old. 2. She hates chocolate cake but loves chocolate. 3. Jenner was named the youngest self-made billionaire by 'Forbes' at the age of 21.4. She co-wrote a young adult novel, Rebels: City of Indra, with her sister.5. She has revealed that she wants to pursue an acting career.