The truth about how much genetics have to do with your fertility

As an early 30-something, I recently started noticing a shift in conversation topic among my peers. Where we once talked about which bars to try on Saturday night and how to find an affordable apartment that isn’t cockroach-infested, long talks now center on career aspirations, finding a life partner, and if we want kids—and if so, exactly how long we can wait to start “trying.”

While my friends’ reasons for not having kids at the moment vary (some people are still paying down student loans; other people might not have found the right partner), one thing I hear consistently across the board goes something like this: “My mom got pregnant with me on her first try and she was 39, so I feel like I can wait.” Or alternatively: “My mom had a really hard time getting pregnant, so I should probably start early.”

Long story short, it seems like a common assumption that our mothers’ ease (or difficulty) with fertility predicts our own. But is there any truth to this? I asked the experts to do some myth-busting for me.

Is fertility genetic? Kind of.

Hate to break it to you, but just because your mom got pregnant naturally on her first try as a 40-something doesn’t mean you necessarily will have the same luck. “Every egg and sperm combination is different, so in that respect, fertility is somewhat random and hard to predict,” says Lynn Westphal, MD, FACOG, chief medical officer at Kindbody, a full-service women’s health and fertility platform. “Coming from a ‘fertile family’ doesn’t necessarily mean you will be fertile as well.”

That said, certain conditions that impact fertility can be genetic. “Age of menopause runs in families—so if a mom went through menopause at 40 (average age being 51), her daughter would have a somewhat higher chance of having an early menopause—meaning a slowing down of fertility earlier on,” says Mary Jane Minkin, MD, a clinical professor of obstetrics and gynecology at Yale University. “So for example, if I have a patient who tells me all the ladies in her family went through menopause at age 40, I would encourage her to think about childbearing earlier than she might have previously.”

Other conditions like endometriosis and PCOS—both of which can impact fertility—can be genetic as well. “If your mom had endometriosis, which [likely] hindered her getting pregnant, and you have had some nasty periods or pain with intercourse, I would also suggest checking in with your gynecologist,” Dr. Minkin says, because you may be at risk of endometriosis—and thus fertility problems as well. “We have so many more options these days for treating endometriosis.”

The same rule generally applies to men. While male fertility isn’t automatically determined by the virility of family members, Dr. Westphal says men can carry certain genetic variants that lead to infertility. “This can happen in the form of a chromosomal rearrangement or missing a gene on the Y chromosome,” she says. “Most men don’t know about it until they have testing done that shows a low sperm count.”

What should you do if you’re worried about your fertility?

According to the American Pregnancy Association, people should seek the help of a fertility specialist if they’re under 35 and have been trying for 12 months to conceive without success, or if they’re over 35 and haven’t had success after six months. But as they say, knowledge is power—and if you want to get a better picture of your fertility now, there are a few ways to do that.

“You can assess how well you’re ovulating pretty easily—you can use an at-home ovulation predictor kit to make sure you’re ovulating every month,” says Dr. Westphal. (There are tons of fertility-tracking apps on the market that can help you do this.) Just knowing when you ovulate in your cycle could help you better time any potential baby-making efforts in the future. She says if it seems like you’re not ovulating, “it’s time to check in with your gynecologist.”

There are also certain lifestyle factors that can impact fertility for both men and women that can be addressed now, even if you’re not sure you want to have kids (or aren’t ready at this exact second). For example, women who have an extremely low or an extremely high BMI may have problems getting pregnant. Stress can potentially affect a woman’s ability to conceive—a 2014 study found that women with high levels of the enzyme alpha amylase (which, like cortisol, is associated with stress) had a high risk of being infertile.

“If a man is drinking a lot it can interfere with sperm production—so less alcohol can certainly be helpful,” adds Dr. Minkin. “Similarly, minimizing smoking (cigarettes and marijuana) can be helpful, too.” (Smoking marijuana has long been associated with lower sperm counts in men—although that thinking has been challenged recently with a new study.)

The bottom line: Your genetic makeup has less to do with fertility than you’d think. But if there’s something in your family history (say, a predisposition towards early menopause) that has concerned about your potential ability to have kids, definitely raise it with your OB/GYN. Even if you don’t know if you want kids at all, it can be helpful to know your options.

If you’re interested in having a baby, check out these fertility-boosting foods. And if you have zero interest in getting pregnant any time soon, here’s everything to know about the IUD.