Older fathers pass on more new genetic mutations to their children than younger fathers, increasing their children's risk of autism, schizophrenia and other diseases, new research published Wednesday shows. While advanced maternal age is a major cause behind rare chromosomal problems such as Down syndrome in babies, the latest findings add to growing evidence suggesting that at conception it is the father's age— rather than the mother's—that is the main factor behind the passing of new hereditary mutations to children.