Want a successful marriage? Make sure you have sex when you're ready. According to a new study, women who are sexually active early in their adolescence--specifically, before age 16--are more likely to divorce. Researchers at the University of Iowa used the responses of 3,793 women who are married or have been married at some point in their lives from the 2002 National Survey of Family Growth to examine the relationship between the age at which they had their first sexual experience, and the success...