Why your baby’s crying might be in their genes, not your parenting

It starts with a scream in the middle of the night. Then again at 3:00 a.m. And again just as you're about to drift back to sleep. For new parents, the cycle of crying, comforting, and worrying becomes a round-the-clock ritual. And somewhere in that blur of sleep-deprived caregiving, a gnawing question forms: Is it something I’m doing wrong?

But according to a growing body of research, how much your baby cries might have less to do with your soothing skills and more to do with what your baby inherited. A study of hundreds of twin pairs conducted by scientists in Sweden has found that genetics play a substantial role in infant crying patterns, sleep quality, and the ability to be soothed.

This isn’t about blame. It’s about biology—and the systems shaping early behavior long before parenting styles come into play. And understanding that system might help parents recalibrate their expectations, reduce guilt, and focus more on rhythm than resolution.

For many new parents, especially mothers, crying becomes the barometer of competence. The quieter the baby, the more "successful" the parent. This unspoken metric often translates into immense self-blame when an infant cries frequently or refuses to be soothed.

What complicates things is that infant crying has long been culturally interpreted through a behavioral lens. "He’s spoiled." "She just wants attention." "You need to let him cry it out." These narratives place crying within the realm of parental control—and by extension, responsibility.

But science is now revealing a more complex picture. The Swedish twin study, one of the largest of its kind, found that crying duration and ease of soothing in the first months of life are more heritable than previously assumed. Twins with the same DNA cried at similar durations, regardless of parental approach. In contrast, fraternal twins, who share only half their genes, showed more variation.

Before interpreting crying as a signal of failure, it’s worth remembering what it actually is: a communication system. Crying is a baby’s primary way of expressing discomfort, hunger, overstimulation, or pain. In evolutionary terms, it's a survival mechanism.

But like all biological systems, there’s variation. Just as some adults are more prone to anxiety, some infants may be more sensitive to external stimuli or slower to self-soothe. These differences don’t mean anything is wrong. They mean the system is tuned differently.

The Swedish research suggests that a baby’s neurological baseline—their default stress reactivity, their ability to regulate arousal, and their sleep consolidation pattern—is genetically influenced. This means that for some babies, soothing might always take longer. The volume might always be higher. And that’s not a failure of nurture. It’s a reflection of nature.

It’s easy to tell a parent not to take their baby’s cries personally. It’s much harder to feel that way when you’re exhausted, your baby won’t sleep unless you’re holding them upright, and everyone around you is offering unsolicited advice.

Cultural narratives around "good babies" and "natural parenting" can reinforce unrealistic expectations. In some societies, babies who sleep through the night early are celebrated. Parents who respond instantly are praised for sensitivity. Parents who let babies cry are critiqued for detachment. Meanwhile, the real variation in infant temperament goes unacknowledged.

What this new genetic research does is offer a quiet reframing: perhaps your baby isn’t difficult. Perhaps your baby’s nervous system is just built differently.

Knowing that some babies are biologically wired to cry more doesn’t mean we should stop trying to soothe them. It means we need to rethink how we soothe—and for how long we expect it to work.

Soothing isn’t about silencing. It’s about co-regulating: helping a baby move from high arousal to calm through physical presence, tone of voice, and predictable rhythms. For genetically sensitive babies, this process might take 10 minutes instead of 2. It might involve walking, bouncing, or layering multiple sensory cues.

But the biggest shift isn’t in what you do—it’s in what you expect. If your baby cries more than your friend’s, that doesn’t mean you’re doing less. It means your rhythm will look different. Design your night feeds and naps with that in mind. Build in buffer time. Share the load if you can. Lower the performance pressure. This isn’t a parenting test. It’s a nervous system choreography.

Most pediatricians agree that crying tends to peak around 6 to 8 weeks of age and then gradually decline. But for some families, the crying remains intense beyond the typical curve. These cases often get labeled as "colic" or dismissed as temperament.

But with genetic research showing strong heritability, we may need to rethink how we frame this experience. Instead of assuming extended crying is pathological or rare, we might see it as part of the wide spectrum of infant behavior—especially in babies with heightened sensory processing or slower transitions between states.

This doesn’t rule out medical issues. Of course, reflux, allergies, or developmental conditions should be assessed. But if your baby is healthy and still cries more than average, this research suggests it’s likely not your fault.

The same Swedish study also found that sleep quality in early infancy follows similar genetic patterns. Some babies consolidate night sleep quickly; others remain frequent wakers for months. This too is often misinterpreted as a parenting gap.

The truth is, while routines and sleep hygiene matter, they are layered on top of a baby’s inherited circadian sensitivity and arousal thresholds. You can’t train a baby to sleep through the night if their nervous system isn’t developmentally ready. But you can build a home rhythm that supports their progression.

This means dimming lights earlier, using consistent pre-sleep rituals, and avoiding overstimulation. It also means recognizing that your baby’s sleep style might require more flexibility than your schedule prefers—and that’s not a regression. It’s an accommodation.

In Western parenting culture, there’s often an emphasis on control. Getting your baby to sleep, getting them to stop crying, getting them on a schedule. But the research on infant genetics suggests that co-regulation is a more useful framework.

Instead of seeing your job as calming the baby on demand, think of yourself as providing scaffolding—a steady presence that helps them learn to come down from stress. This may not yield instant quiet. But over time, it teaches resilience.

Co-regulation can look like humming the same tune every night. It can look like slowing your own breathing while holding your baby. It can mean holding space, literally and figuratively, for the noise to pass.

There will be moments when your baby quiets almost instantly. When the swaddle, the shushing, and the shoulder-rocking align like clockwork. Those moments feel like magic. But they’re not magic. They’re system sync.

What worked that night may not work the next. That’s because infants are dynamic systems—not puzzles to solve, but processes to join. The more we understand infant crying and sleep as genetically-influenced regulatory systems, the less pressure we put on parents to perform perfection. Soothing becomes a ritual of connection, not correction. And the most powerful ritual of all is showing up again, and again, and again—even when it’s loud.

Parenting an infant who cries a lot is exhausting. But the next time someone suggests you’re doing something wrong, remember this: biology, not failure, might be the louder voice.

Your baby’s tears are not a scoreboard. They are part of a regulation system learning to find its rhythm—with you as its steady partner. This isn’t about silencing. It’s about attuning. And that, genetics and all, is enough.