If you could find out how long you had to live, would you want to know? Well, for those brave enough to seek an answer, scientists studying aging at Northwestern University have discovered a surprising biological cue that could help predict length of life, according to MedicalXpress.com.The clue? Look to dear old dad. In fact, the older, the better. Researchers found that fathers who waited until they were older to have children tended to spawn kids who were biologically equipped to live longer.MORE: How To Stay Young Forever“If our recent ancestors waited until later in adulthood before they reproduced, perhaps for cultural reasons, it would make sense for our bodies to prepare for something similar by investing the extra resources necessary to maintain healthy functioning at more advanced ages,” said Christopher W. Kuzawa, co-author of the study and associate professor of anthropology at Northwestern, when describing the working hypothesis of the study.The study, conducted in the Philippines, confirmed a direct correlation between the age of a man when he became a father and the average length of his children’s telomeres at birth. Telomeres are strands of repetitive nucleotides that are found on the ends of chromosomes and are believed to protect the chromosomes from deterioration. Because telomeres shorten each time the chromosomes replicate, the longer they are to begin with, the more resistant the DNA is to aging. Or at least, that’s the theory.Interestingly, the study didn’t just find the correlation existed between fathers and their children, but also between grandfathers and their grandchildren. In other words, the effect seems to carry across at least two generations. So even if your father reproduced at a young age, if his father reproduced at a later age, you may still reap the benefits of longer telomeres.MORE: How To Live To 100, or Even 150…“The idea that information about the environment can be passed on biochemically from one generation to the next is certainly not something new,” said M. Geoffrey Hayes, co-author of the study and assistant professor of medicine at Northwestern’s Feinberg School of Medicine. “But what is quite unique in the case of our telomere study is that we’re seeing an association across more than one generation.”Further study is needed over a longer period of time to determine if the children of older fathers really do live longer, but the knowledge that they are born with longer telomeres has researchers confident that the answer will be yes.Even so, the researchers cautioned men against delaying reproduction until too late in life. Previous studies have shown that older fathers are also more likely to pass along harmful mutations to their offspring. So there are risks involved in choosing to be an older father, too.QUIZ: How Healthy Is Your Life?