Mark Regnerus, director of the at Calvin College, thinks religious parents need to talk more frankly with their kids about sex. He's come to that conclusion after completing a national study of over 12,000 teens and parents.

"Parents who value their faith very much appear at first to talk more about these topics," Regnerus says, "but after I account for the conversations they have about the morality of adolescent sexual behavior, then those relationships disappear. When devoutly religious parents, by several measures, are communicating with their teens about sex, it is primarily values and not information they are conveying."

And, Regnerus notes, white churchgoing parents displayed even lower patterns of such communication than those of most other races.

The lack of communication, says Regnerus, is alarming.

"Parents everywhere are overestimating what their kids know (about sex)," he says. "They (parents) think teens know a lot, but they really don't when you quiz them (which our data did)."

Using nationally representative data from both parents and their teenagers, Regnerus found that parents who attend church irregularly or not at all are more apt to talk with their kids about both sex and birth control than churchgoing parents.

That's understandable, he says, given religious parents' concerns about adolescent sex -- avoiding it remains one of the markers of a "well-lived" adolescence in the Church. But it does children a diservice he believes.

"Adult respondents are not grateful later in life for having learned little to nothing from their parents about what sex means both physically and emotionally," he says. "People whose parents don't talk about it find themselves wishing they had been better informed."

Regnerus notes that these are important discussions not just because of their implications later in life, but also for their impact on the lives of teens. According to the Centers for Disease Control and Prevention, despite recent declines, the birth rate for American teens remains among the highest among all developed countries. Teenagers also account for a sizable share of the 15 million new cases of sexually transmitted diseases that occur each year in the U.S.

On Tuesday, November 27 at 3:30 p.m. at Calvin, Regnerus will discuss his recent research on this topic in a talk called "What Parents Say and What Teenagers Know About Sex."