Andrew, 28, miserably slams his laptop shut. He was fully prepared with his lotion, his tissues and his video of “Homewrecking Babysitters 5,” but his weiner won’t play ball. “Teen” porn was once his favorite masturbatory material, but now it suddenly seems tainted.

“Is it possible I’m too old,” he later asks me, “to continue watching teen porn?”

Before solving Andrew’s existential crisis, I wonder, what’s so great about teen porn in the first place? It’s consistently one of the most popular porn search terms on the internet, even though it’s totally illegal to diddle anyone under the age of 18, leaving only two lawful years to fulfill this fantasy. Yet “barely legal” content and the fetish of fucking an 18-year-old still thrive as signs that our fascination with youth is dominating pornography.

The simple answer to the titular question should be: never. You should be able to explore your fantasies for naughty little schoolgirls without internalized shame and stigma. But you wouldn’t be here if shit were that simple. So the more complicated answer will have to be: whichever one of these milestones seems most appropriate (or inappropriate) to you.

When you have your first daughter

Andrew (not his real name) is convinced the birth of his baby daughter has re-wired his brain to find teen porn more concerning than arousing. Those naive young girls throwing caution to the wind and throwing dicks into their mouths don’t turn him on — they worry him.

Until fatherhood, the rationalization behind his “jailbait” fetish was an appeal to nature. Humans’ primitive instinct to reproduce draws men to women when they’re most fertile, as the logic goes, in their late teens.

However, the science is pretty clear that ladies’ peak fertility happens in their 20’s, years after they’ve passed the age of consent and outlived the title of “barely legal.” Without that “human nature” argument on his side, the defense of being driven by animal instincts falls to the wayside.

Now, he’s forced to see these young ladies not as sexual conquests, but as disobedient daughters, making idiotic decisions that will inevitably destroy their marketing careers.

When you use it to cope with the anxiety of aging

Around that age when gray hairs start sprouting and, some men might begin to fear becoming sexually inadequate.

With sexual confidence at a lifetime low, it starts to seem a lot more appealing to find an innocent, even virginal, young lady who’s longing for sexual initiation at the hands of an experienced older man. That sexual naivete is an assurance that no matter how unimpressive you might be in the bedroom, she’s sure to be dazzled anyway.

As porn star Janice Griffith explains it, this is the repeating narrative of every teen porn film —  a male authority figure catches a female subordinate (a student, babysitter, or friend’s daughter) doing something her character shouldn’t be and offers to seduce the man in exchange for keeping her secret. It’s a mildly predatory fantasy the story caters to — a desire for authority and control over an impressionable young woman.

Unfortunately, a piece of jailbait in a cheerleading outfit isn’t the solution to newfound wrinkles.

When you’re old enough to be her father

You don’t have to have a daughter to feel rightfully creepy jerkin’ it to “Tiny Teenage Anal Virgin Amateurs.” Consider if it’s realistic that you could have given birth to this young slut, and if the answer is yes, maybe that should make you feel a little weird about tugging your manhood to the sight of her post-pubescent appearance.

This question of “could you be her father?” is important, though, for those readers who were super butthurt to open this article and not find a simple number to assuage their fears that they might be too old for teen porn.

Using the average age that American men become new fathers, around 31, and assuming the piece of ass in your typical teen flick is sincerely 18 and “barely legal,” then any age past 49 is old enough to be her father, and consequently might be too old to be fapping it to porn featuring their potential offspring.

TL;DR: 49