Why would he want to silence criticism of his book when that criticism stirs up interest and free publicity?
I have never seen or heard anything said by Brown that indicates he thinks Christ and Mary Magdalene really had a child. Where are you getting this?
There are several believers on this thread. Have you read Dan Brown's web page? He clearly indicates he believes the theories in his book. Lots of people, especially the anti-Catholic/Christian types, eat up this stuff and buy into it.