Nicole Richie's two children are complete opposites.

The 30-year-old fashion designer says that while her two-year-old son Sparrow is ''wild'' like his mother, daughter Harlow, four, takes after her cautious father, Good Charlotte rocker Joel Madden.

She said: ''My daughter looks exactly like me, and she has Joel's personality. She's very careful. She doesn't make a move without fully thinking about what the consequences would be and what that means.

''[Sparrow] looks exactly like Joel and has my personality. He's just wild. I'm in for the ride. We've had broken fingers, we've been to the hospital - you cannot take your eye off of him for a second. He is just a full, free spirit.''

Nicole - who was famed for her party-girl lifestyle before becoming a mother - admits she had little in Common with husband Joel, 32, when they first met in 2006.

She told Ocean Drive magazine: ''He's from southern Maryland. He's very family-oriented. He grew up with four brothers and sisters. When we met, I was definitely going through a difficult time with my family, and having him have such a strong foundation really opened The Doors and brought both of our families together.''

Looking back at her wild-child behaviour with former best friend Paris Hilton in reality show 'The Simple Life', Nicole insists she has matured a lot since then.

She said: ''You have to remember that I was 20 years old. I don't know anybody who can look back at who they were at 20 and say, 'I'm the exact same person'.

''It's all about evolving and growing. Who we are in our 30s is obviously very different than who we are in our 20s.''