Jonathan Zimmerman is a professor of education and history at New York University. He is the author of Small Wonder: The Little Red Schoolhouse in History and Memory and three other books.

In 1985, the founder of modern American sex education gave a controversial speech about erections in fetuses. To Mary Calderone, who had started the Sexuality Information and Education Council of the United States back in 1964, new evidence about arousal in male fetuses demonstrated once and for all that children were sexual beings.

Nonsense, said conservatives. To critics of sex education, childhood was — or should be — a time of sexual innocence. Racy movies, TV shows and magazines made kids prematurely interested in sex. And so did sex education, which robbed them of their natural virtue and replaced it with tawdry thoughts and feelings.

I thought of this debate as I read the comments by Rep. Michael Burgess, R-Texas, during the House debate on Monday over a bill that would ban almost all abortions after 20 weeks of pregnancy. According to Burgess, fetuses do not simply experience sexual arousal; they actively arouse themselves.

Liberal commentators and late-night comedians pounced on Burgess’ remarks, which are just the latest salvo in America’s long-running culture war over abortion. But they also signaled a truce in an even older cultural conflict, about sexuality itself. After denying childhood sexual feelings for nearly a century, conservatives are starting to acknowledge them. And that’s good news for anyone who cares about the sex education of our young....