Finally, there is some good news for older dads. A new study shows that their children and even grandchildren may get a health benefit because of their older age. It's based on research into something called telomeres--tips on the ends of chromosomes      Some previous studies have connected having longer telomeres with better health and longer lives. Telomeres haven't been proven to cause those benefits in the general population, but a number of researchers think they may hold secrets for things like longevity and cancer.     As you age, telomeres shorten. However, previous studies have shown that the older a man is when he becomes a father, the longer the telomeres his children tend to have. The new research confirms that and finds it's extended to the grandchildren. That's a cheerier result for older dads than some other studies in recent years that indicate their kids are at higher risk for things like autism      Carol Greider of Johns Hopkins University, who shared a Nobel Prize in 2009 for telomere research but didn't participate in the new study, said it's no surprise that the telomere effect would extend beyond children to grandchildren. She also said that since older fathers also tend to pass more potentially harmful genetic mutations , it's "not at all clear" whether advanced paternal  age gives an overall health benefit to children. In a statement, the researchers who conducted the study said their study shouldn't be taken as a recommendation that men reproduce at older ages because there's a risk of genetic mutations.     Some previous studies of the impact of older fatherhood have been less encouraging. In 2010, for example, at least two big studies confirmed a link to having children with autism. In 2008, a big Swedish study strengthened evidence linking bipolar disorder  to older paternal ages. What is the main idea of this passage?
Older parents are greatly encouraged by some good news. Dads can have a great influence on their children's development. Older dads no longer need to worry about their children's health. Older dads might benefit the health of their children and grandchildren.