I just could not understand why such a thing would take place, but after watching a few videos I got an understanding of why they do it. I myself would never do that it just does not make since to have that happen.
I read an article on this sight: http://www.religioustolerance.org/fem_cirm.htm and it said Muslim women circumcise their girls because Sunnah the writings of the prophet Muhammad says that they must. The also say that they do it because when their husbands goes on a Jihad for a year, they do not want there women to be tempted to commit adultery.
In some African villages they believe that if you do not cut of the clitoris it will cause the whole family to die, so if a girl refuses to have the procedure done she is disowned and thrown out of the village. The list goes on for why women in different countries perform FGMs on their children and why they allow it to happen to them copy and past the links below in your address box and watch.
Here is a couple of Video links:
http://www.youtube.com/watch?v=mspMEMD8OeE&feature=related
http://www.youtube.com/watch?v=5z-PnwJ0_xk&feature=related
http://www.youtube.com/watch?v=9kNMC65pNsg&feature=related