If you were to read biology professor Bill Schutt’s new book “Cannibalism: A Perfectly Natural History,” you’d have lots to talk about at the dinner table.

There are, for instance, sections on how cannibalism is portrayed in popular culture, news stories and historical texts. Schutt investigates -- with dark humor -- how cannibalism works within different animal species and how it’s understood by humans of different nations, cultures and religions. Somehow he makes the subject fascinating, rather than gruesome.

We learn about how cannibalism is practiced in the Catholic Church -- some members believe in “transubstantiation,” wherein the wafer and wine literally turn into the blood and body of Christ during the sacrament of communion -- and in middle-class American households. At one point, the author flies to Plano, Texas, to eat a woman’s placenta, which her husband cooks up, osso buco-style, for Schutt’s approval.

But Schutt’s scholarship also inadvertently ended up teaching my kids a lesson about how today’s tech gadgets can infiltrate the most private corners of their lives.

Let’s rewind to November 2015, when the WNYC podcast “Note to Self” first aired an episode titled “Is My Phone Eavesdropping On Me?” In a conversation with writer Walter Kirn, the idea that our mobile apps “listen” to us via the phone’s microphone was explored in depth. Afterward, my husband reported that he’d had an experience similar to what Kirn described -- with his phone nearby, he had mentioned a consumer product and, shortly thereafter, saw ads for it in his apps.

We promptly gathered all the cellphones in our home and adjusted their privacy settings to ensure that no apps had permission to access the microphone or camera.

Fast-forward to three weeks ago, when my husband started seeing news items on his browser’s homepage with headlines including words that he had used at work. Even though his iPhone and iPad are programmed to not allow access to the microphone, he set out to test if they were somehow picking up his conversations.

For 10 days he dropped “Jack Daniel’s” into family conversations in proximity of the devices. Sometimes just “Jack” and sometimes just “Daniel’s” in a variety of contexts, but most of the time in reference to the whiskey -- a product we don’t usually mention at home or purchase.

Nothing happened. No boozy Spotify commercials came his way, no prescient news headlines; we assumed that either nothing was listening in or the popular whiskey brand doesn’t use high-tech eavesdropping to serve up digital ads and drive demand.

Then, a week ago, I started talking about cannibalism.

Nightly, during dinner, I dropped a dose of newfound cannibalism knowledge on my family. It made for spirited discussions about how different cultures honor their dead, what one is willing to do to survive traumatic starvation and how global climate change might ultimately exacerbate cannibalism.

I finished Schutt’s “Cannibalism” on Sunday morning. We discussed his placenta osso buco at breakfast and about an hour later, my older son -- who, when he turned 18 in December, got a new iPhone -- turned to me and said, “I’m seeing more about cannibalism in clips on Facebook.”

Nothing too horrible -- newsy items, like from the website Business Insider, about “The most fascinating examples of [animal] cannibalism that exist today” -- but he reported seeing more and more just in the past week.

We checked his privacy settings and, sure enough, his social media apps had, by default, been allowing his microphone to listen in on his life.

He quickly readjusted all his privacy settings and learned that his parents may not be unnecessarily paranoid. The homing device in his pocket is not only there for his convenience, but, increasingly, so marketers can make money off of his innocent belief that the content he sees on his social networks and preferred websites is serendipitous.

Facebook, for one, has denied that it uses your phone’s microphone to influence your news feed or the ads you see. But our phones can and will listen in on our conversations if we don’t proactively keep them from doing so -- and so will our laptops, tablets and desktop computers. Anything with a camera or a microphone is suspect.

To protect yourself from this sort of invasion, you just need to spend a few minutes web searching for tips on how to adjust your privacy settings or block your hardware’s audio and video ports.

Do it now. Your kitchen, bedroom or car conversations -- about cannibalism or any other topic -- are none of the internet’s business.