At one time, it was common for American families to have six, seven or even more children. Today, the sight of so many kids makes many people stop and wonder "Why?". Plenty of people have been asking that ever since California mom Nadya Suleman gave birth to octuplets earlier this month - especially after having six more at home already. Celebrities such as Angelina Jolie and Brad Pitt - who have large families - have long been an endless source of public curiosity and speculation. So, why do some people desire unusually large families? Here are the details, courtesy of MSNBC, and Gayle Peterson, family therapist and author of Making Healthy Families.

Of course, some parents cite religious or cultural reasons for having a large family and some simply want to help children in need - and adopt or foster all they can. However, sometimes, Dr. Peterson says the desire to keep having kids goes a lot deeper. In certain cases, it can become a compulsion, an obsession or even a "baby addiction." The current book of psychiatric diagnoses has no entry on baby addiction, but mental-health professionals say they often see patients - mostly women - who fit the bill. These patients desperately want to keep having babies, even when they already have several children and aren't managing their family well. Because once their youngest becomes a toddler and starts developing a mind of their own, they miss the intensity of the newborn period - and crave another baby. Experts say that's a big red flag.

Dr. Sudeepta Varma, a psychiatrist at New York University Medical Center, says there's no "ideal" family size for everyone. However, each couple should think through how many children they want and can manage, afford and provide for emotionally. In Suleman's case, she's not married and has no job - plus some of her older kids have disabilities and need extra care. In Brad and Angelina's case, they can more than afford the six kids they have. Experts say an alternative for couples who feel that their family isn't complete is to get their "baby fix" in other ways - such as working in a daycare center or volunteering in a church nursery. Because you don't have to keep having babies in order to show your love.