A relatively recent article in Nature (Kong et al. Rate of de novo mutations and the importance of father's age to disease risk. Nature Volume: 488 Issue: 7412 Pages: 471-475 DOI: 10.1038/nature11396 Published: AUG 23 2012) analyzed what may be the largest amount of parent-child DNA sequence data so far generated to identify novel mutations. Surprisingly, they find that almost all of the variation in the number of mutations is explained by the age of the father.
My apologies if this article was diaried before, but if so, I didn't find it!