It's long been known that babies of older moms can have more health problems, but studies have now linked mental illness to advanced paternal age:
Researchers analyzed Swedish national registry data from more than 80,000 people, including 13,428 with bipolar disorder who were born between 1932 and 1991.
The risks started increasing around age 40 but were strongest among those 55 and older. Children with these dads were 37 percent more likely to develop bipolar disorder than those born to men in their 20s.
They also faced more than double the risk of developing bipolar disorder before age 20. Scientists call that early onset disease, and although they have long known that bipolar disorder tends to run in families, early onset disease has been thought to be most strongly linked with genetics.
http://www.cnn.com/2008/HEALTH/conditions/09/01/older.dads.bipolar.ap/index.html?iref=mpstoryview - Thanks Tiffany!