They arent all hers,she adopted some of them,but she wont say how many. 
Personal life (Marie Osmond)
Osmond has been married and divorced twice and has eight children in total from the two marriages. She married her first husband Stephen Craig, a Brigham Young University basketball player, in 1982. They were married in an LDS temple wedding ceremony. They had one child, Stephen James Craig, Jr. (Later renamed Stephen James Craig Blosil), who was born on April 20, 1983. Osmond and Craig divorced in the mid 1980s after Craig admitted that he was not ready to be either married or a father.
On October 28, 1986 Osmond married Brian Blosil, also in an LDS temple. While married to Blosil, Osmond had two more children, Rachael Lauren in 1989 and Matthew Richard in 1999.
They also adopted five children: Jessica Marie in 1987, Michael Brian in 1991, Brandon Warren in 1997, Brianna Patricia in 1998, and Abigail Michelle in 2002. Brian Blosil also adopted Marie's son from her previous marriage as his own, Stephen James Craig Blosil.
(Extract from http://news.bbc.co.uk/1/hi/england/manchester/8354316.stm )