Among the dangers of the growing acceptance and legalization of gay marriage is that it will discourage honest research into its effects on children, traditional marriage and families. Society has begun down the road of redefining an age-old institution without much understanding of long-term outcomes and what they might mean for society as a whole.

Political correctness has become a huge stumbling block toward legitimate research, as authors of studies that identify problems with same-gender marriage and child rearing can attest. Meanwhile, solid research is needed in order to understand what this dramatic shift in family structure means.

A new study by economist Douglas Allen of Simon Fraser University, using Canadian census figures, sheds a disturbing light on the question.

Canada is an ideal place to study the effects of same-gender marriage on children, as it has embraced gay marriage for eight years and provided equality in taxes and benefits to such unions for much longer. The Canadian census identifies children living with gay couples, as well as those living in single-parent households and those headed by traditional male-female unions.

The study, published in the Review of the Economics of the Household, finds that the children of gay and lesbian couples are much less likely to graduate from high school than the children of traditional marriages. The problem is more acute among girls than boys.

Allen used a 20 percent random sample from the 2006 census to draw his conclusions, using regression models and controlling for variables. The differences he found in graduation rates cannot be explained away by the education levels of the parents, as the same-sex parents tended to have higher education levels than the traditional opposite-gender ones.

The study found that children of gay and lesbian couples in Canada are only 65 percent as likely to graduate from high school as children of opposite-gender parents. Girls raised by same-gender male couples, startlingly, are only 15 percent as likely to graduate. Girls raised by lesbian couples are 45 percent as likely to graduate.

In an interview with, Allen said the Canadian census offers a far better way to measure such things than the U.S. census, which doesn’t identify same-gender couples. Previous studies that claimed to find no difference between the outcomes of children in various familial situations were flawed because of the lack of such specific data.

Allen makes the point that he does not make any claims as to why things are as he discovered them. He did tell, however, “It makes sense to me that fathers and mothers are not perfect substitutes. Indeed, mothers may provide some parenting services that a father cannot provide, and fathers may provide parenting services that mothers cannot. These services may be necessary for girls but not necessary for boys.”

We would call such an observation self-evident, although we believe the gender models men and women separately provide are as important for rearing boys as for girls.

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Not surprisingly, Allen already has been labeled a bigot and “evil” in some quarters, further illustrating how difficult it will be for science and research to inform this important issue.

As National Organization for Marriage co-founder Maggie Gallagher wrote two years ago, “Amid the spectacular myriad of relationships that human beings create, marriage is unique for a reason: these are the only unions that can create life and connect those new young lives to the mother and father who made them.”

It makes no sense for society to fundamentally alter such an institution without understanding the consequences.