This week, Massachusetts began handing out marriage licenses to same-sex couples. Amid the cheers, there are the doomsayers who predict that same-sex weddings will mean the end of civilization as we know it. Conservative religious leader James Dobson warns that Massachusetts is issuing “death certificates for the institution of marriage.” And conservative pundit Stanley Kurtz claims to have found the “proof” that the institution will see its demise: Gay marriage helped to kill heterosexual marriage in Scandinavia. Indeed, Kurtz has become a key figure in the marriage debate: He and his statistics have been taken up by conservatives to support their argument that gay unions threaten heterosexual marriage. He has shown up in Congressional hearings, lawsuit filings, newspapers, debates, and anti-gay marriage videos across the country.

But Kurtz’s smoking gun is really just smoke and mirrors. Reports of the death of marriage in Scandinavia are greatly exaggerated; giving gay couples the right to wed did not lead to massive matrimonial flight by heterosexuals.

Currently there are nine European countries that give marital rights to gay couples. In Scandinavia, Denmark (1989), Norway (1993), Sweden (1994), and Iceland (1996) pioneered a separate-and-not-quite-equal status for same-sex couples called “registered partnership.” (When they register, same-sex couples receive most of the financial and legal rights of marriage, other than the right to marry in a state church and the right to adopt children.) Since 2001, the Netherlands and Belgium have opened marriage to same-sex couples.

Despite what Kurtz might say, the apocalypse has not yet arrived. In fact, the numbers show that heterosexual marriage looks pretty healthy in Scandinavia, where same-sex couples have had rights the longest. In Denmark, for example, the marriage rate had been declining for a half-century but turned around in the early 1980s. After the 1989 passage of the registered-partner law, the marriage rate continued to climb; Danish heterosexual marriage rates are now the highest they’ve been since the early 1970’s. And the most recent marriage rates in Sweden, Norway, and Iceland are all higher than the rates for the years before the partner laws were passed. Furthermore, in the 1990s, divorce rates in Scandinavia remained basically unchanged.

Of course, the good news about marriage rates is bad news for Kurtz’s sky-is-falling argument. So, Kurtz instead focuses on the increasing tendency in Europe for couples to have children out of wedlock. Gay marriage, he argues, is a wedge that is prying marriage and parenthood apart.

The main evidence Kurtz points to is the increase in cohabitation rates among unmarried heterosexual couples and the increase in births to unmarried mothers. Roughly half of all children in Norway, Sweden, and Denmark are now born to unmarried parents. In Denmark, the number of cohabiting couples with children rose by 25 percent in the 1990s. From these statistics Kurtz concludes that ” … married parenthood has become a minority phenomenon,” and—surprise—he blames gay marriage.

But Kurtz’s interpretation of the statistics is incorrect. Parenthood within marriage is still the norm—most cohabitating couples marry after they start having children. In Sweden, for instance, 70 percent of cohabiters wed after their first child is born. Indeed, in Scandinavia the majority of families with children are headed by married parents. In Denmark and Norway, roughly four out of five couples with children were married in 2003. In the Netherlands, a bit south of Scandinavia, 90 percent of heterosexual couples with kids are married.

Kurtz is also mistaken in maintaining that gay unions are to blame for changes in heterosexual marriage patterns. In truth, the shift occurred in the opposite direction: Changes in heterosexual marriage made the recognition of gay couples more likely. In my own recent study conducted in the Netherlands, I found that the nine countries with partnership laws had higher rates of unmarried cohabitation than other European and North American countries before passage of the partner-registration laws. In other words, high cohabitation rates came first, gay partnership laws followed.

A subtler version of Kurtz’s argument states that the advent of registered partnership caused an increase in cohabitation rates and children born outside of marriage (nonmarital births). If that were true, then we would expect to see two patterns: Cohabitation rates and the nonmarital birth rate would rise more quickly within a country after it passed partner registration laws; and the rise in the nonmarital birth rate would be greater in countries that had such laws than in countries that do not recognize same-sex partnerships.

Kurtz’s argument fails both tests. From 1970 to 1980, the Danish nonmarital birth rate tripled, from 11 percent to 33 percent. Over the next 10 years, it rose again to 46 percent and then stopped rising in 1990s after the passage of the 1989 partnership law. Norway’s big surge occurred in the 1980’s, with an increase from 16 percent to 39 percent. In the decade after Norway recognized same-sex couples (in 1993), the nonmarital birth rate first rose slightly, then, after a couple of years, leveled off at 50 percent.

Cohabitation rates tell a similar story. In Denmark, from 1980 to 1989, the number of unmarried, cohabiting couples with children rose by 70 percent, but the same figure rose by only 28 percent from 1989 to 2000—the decade after Denmark introduced its partner-registration laws—and then stopped rising. From 2000 to 2004, the number has increased by a barely perceptible 0.3 percent. The fact that rates of cohabitation and nonmarital births either slowed down or completely stopped rising after the passage of partnership laws shows that the laws had no effect on heterosexual behavior.

Furthermore, the change in nonmarital births was exactly the same in countries with partnership laws as it was in countries without. The eight countries that recognized registered partners at some point in the decade from 1989 to 2000 saw an increase in the average nonmarital birth rate from 36 percent in 1991 to 44 percent in 2000, an eight percentage point increase. Among the EU countries that didn’t recognize partners (plus Switzerland), the average rate of nonmarital births rose from 15 percent to 23 percent—also an eight-point increase.

No matter how you slice the demographic data, rates of nonmarital births and cohabitation do not increase as a result of the passage of laws that give same-sex partners the right to registered partnership. To put it simply: Giving gay couples rights does not inexplicably cause heterosexuals to flee marriage, as Kurtz would have us believe. Looking at the long-term statistical trends, it seems clear that the changes in heterosexuals’ marriage and parenting decisions would have occurred anyway, even in the absence of gay marriage.

And all the conservative hand-wringing seems especially unnecessary when you consider the various incentives that encourage American heterosexual couples to marry. By marrying, U.S. couples obtain health-insurance coverage, pensions, and Social Security survivor benefits. Plus, in the United States we are required by law to be financially responsible for our spouses in bad times, since we don’t have Scandinavian-style welfare programs to fall back on.

In addition, American society already wrestles with the social tensions that Kurtz claims have occurred as a result of gay marriage in Scandinavia: deepening divisions over gay issues in churches, the increasing acceptance of lesbian and gay relationships in the media, and the occasional radical voice arguing for the abolition of marriage. Yet heterosexual couples keep getting married—more than 2 million of them every year.

Concerns about the impact of gay marriage on heterosexual behavior are not unique to the United States, of course. European countries that recognize same-sex couples initially had their worriers, too. Over time, however, it became clear that civilization and family life would survive the recognition of gay couples’ rights. Even the conservative governments that came into power have not tried to repeal rights for gay couples in France and the Netherlands.

Both demographic data and common sense show that the dire predictions of Dobson and Kurtz are just cultural prenuptial jitters. Now that gay and lesbian couples are marrying in Massachusetts, we’ll have a home-grown social experiment that will undoubtedly compare to that of Europe: Letting gay couples say “I do” does not lead to heterosexuals saying “I don’t.”