Gay marriage is an inevitable social certainty, writes Frank Rich. “The polls find a clear majority of those ages 18 to 29 in favor of same-sex marriage. In America, generational turnover is destiny — especially when it’s plugged into capitalism. In a country where only half the families are intact heterosexual marriages with children, those that break the old mold are a huge developing market — for weddings, tourism, housing and anything else American ingenuity can conjure up for consumption.”