How Your Baby Will Look Based on Genetics

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People just cannot help it—they love to predict who a baby will look like. Will she have her mother's eyes and her father's hair? Will he be tall or short? Will she look exactly like Mom or nothing at all? It's everyone's favorite game. Even expecting parents love to speculate. But is there any foolproof way to know what your baby will look like?

The Role of Genetics

Although there are many different possibilities for the exact combination of genes your child could inherit, it all comes down to DNA. And, predicting your baby's looks is not as easy as it seems.

Most traits that babies inherit are the result of multiple genes working together to form your baby's appearance.

What's more, when those genes come together, some of the effects are amplified while others are reduced; and still, others are completely turned off.

Scientists have some understanding of why babies develop the features they do. Here are some ways in which your baby's primary features like hair color and eye color are influenced by genetics.

Hair Color

Babies inherit multiple pairs of genes that play a role in determining hair color. Some of these pairs are from Mom and some are from Dad. These genes then determine your baby's hair color as well as eye color and complexion. And although scientists have yet to determine how many genes ultimately determine the exact hue of your baby's hair, they do understand how the process works.

The genes that determine hair color also regulate melanocytes or the color-producing cells in our bodies. Where babies' tresses fall on the spectrum of black to brown and red to blonde may be determined by how many melanocytes they have, what pigment these cells make, and how much of each shade the cells produce.

For instance, eumelanin, a substance within the melanocyte, produces black to brown while pheomelanin produces yellow to red. As a result, the more color-producing cells babies have, and the more eumelanin those cells make, the darker their hair will be. Meanwhile, babies with only a few melanocytes that mostly make very little eumelanin will have light brown to blonde hair. And babies whose cells produce more pheomelanin will have redder hair.

In fact, red hair is one of the few traits controlled by a single gene. When babies get two copies, they will produce lots of pheomelanin and have a head full of red hair. These babies also will have light skin and freckles. This gene causes the skin's melanocytes to clump together, producing freckles. For people with freckles and no red hair, they may have inherited only one of the genes that produce that beautiful ginger hair.

Hair color changes over time, so even if a baby is born with a head full of black hair, this hair color can change.

In fact, hair color is especially prone to change when kids hit puberty. The hormones coursing through their bodies can activate genes that cause their hair to change color or to develop curl.

Eye Color

Most babies are born with bluish-grayish-looking eyes when they are born. The reason for this is that the color-producing cells in the iris of the eye need exposure to light to activate. As a result, it could take up to six months before a baby's eye color stabilizes.

Just like hair color, eye color is determined by melanocytes whose role is secreting the protein melanin where it’s needed. Over time, if melanocytes only secrete a little melanin, your baby will have blue eyes and if they secrete a little more, your baby's eyes will look green or hazel. Meanwhile, brown eyes occur when melanocytes secrete a lot of melanin.

When it comes to determining how much the melanocytes produce, at least two genes influence the shade that develops. These come in two forms, or alleles—one that has brown and blue versions and one that has blue and green versions. As a result, babies' eye color will depend on the combination of alleles they inherit from their parents.

For instance, if both parents have dark eyes, the chances of the baby having dark eyes as well is high since the brown allele is dominant. However, if there are blue eyes on both sides of the family, it is not impossible for two brown-eyed parents to have a blue-eyed child. Keep in mind that eye color is not as cut and dried as people learn in a high school biology class. Still, here is a general overview of what could happen with baby's eye color.

  • If both parents have blue eyes, it is very likely their child will have blue eyes but keep in mind this won't happen every single time.
  • Two brown-eyed parents are likely to have a child with brown eyes, but as in the example above, this is not guaranteed.
  • If one or more of the grandparents has blue eyes, the chances of having a baby with blue eyes increases slightly.
  • If one parent has brown eyes and the other has blue eyes, usually there is about a 50/50 chance the child will have brown eyes.

Height and Build

When it comes to a baby's size, keep in mind that a baby's measurements at birth do not necessarily predict future height and weight. There are many factors that influence a baby's size when born, including Mom's diet while she was pregnant as well as various health conditions.

More than 100 genes code for height, so regardless of initial numbers, babies will grow to their genetically predisposed height.

There are ways to predict your baby's future height if you want. One way to make a rough estimate for a girl is to subtract five inches from Dad's height and average it with Mom's height. So, for a Dad who is 72 inches tall (6'2") and a Mom who is 66 inches tall (5'6"), the average is 67.5 inches (5'7.5"). For boys, add five inches to Mom's height and then average that with Dad's height. Using these same numbers for Mom and Dad, a son could potentially be 71.5 inches or (6'1.5").

Still, there is no foolproof way to determine your baby's future height. Even growth charts can be off. There are a number of genetic factors that determine height. Additionally, nutrition and physical activity also can play a role.

Do Baby Girl Faces and Baby Boy Faces Look the Same?

Most people believe that all babies look the same until they get a little older. As a result, they rely on wardrobe cues like pink clothes, pierced ears, and hair bows to determine if a baby is a boy or a girl. But as it turns out, studies suggest that even without the wardrobe, you will be able to accurately guess 60 percent of the time which babies are girls and which babies are boys.

In fact, in one study that appeared in Attention, Perception and Psychophysics discovered that 76 participants were able to categorize the sex of 120 Caucasian baby faces shown in closely cropped photos more than half of the time.

This study, combined with numerous others, confirmed that if people try hard enough they can distinguish the girl babies from the boy babies most of the time without any external hints.

As babies get older, their features mature. What's more, puberty will cause them to head down different paths as they mature. Studies have shown that adults can categorize a random person's sex from looking at their noses, eyes, or eyebrows.

Is It True Newborns Look More Like Dad?

There is a common belief that babies tend to look more like their fathers than their mothers. The idea is that human evolution favored that children resemble their fathers at birth as a natural way for Dad to be certain the child was his. This theory received some scientific backing in 1995 when a study by Nicholas Christenfeld and Emily Hill was printed in Nature magazine showing that people were much better at matching photos of one-year-old with their fathers rather than their mothers.

However, several studies since then have shown that most infants resemble both parents equally, and one study even suggests that in the first three days of life, the baby looks more like Mom but she will tend to say the opposite, emphasizing the child's resemblance to the father. Some researchers speculate that mothers point out this resemblance without even realizing they are doing it. They theorize that a mother's remarks may be an evolved or conditioned response.

Surprising Benefits to Looking Like Dad

In a Fragile Family and Child Wellbeing study, researchers discovered that babies of single mothers who look more like Dad were healthier one year later than babies who looked nothing like their father. Researchers believe that when babies resemble their fathers, the father is more likely to "see themselves" in the baby and is more likely to interact with, visit, and care for the baby.

The research found that fathers spent an average of 2.5 more days with the child if the baby looked more like them.

In turn, researchers theorize that these frequent father visits allow for greater caregiving, supervision, and support for the child's health and economic needs.

How to Handle It If Your Baby Looks Nothing Like You

Some parents shrug it off when their child looks nothing like them. After all, what's on the inside is all that really matters, right? But it's normal to feel hurt and wonder how to respond when someone says your child looks nothing like you, or even worse when someone asks if you're the nanny. Should you answer their question politely or give them a crash course in genetics?

Having a child that looks nothing like you can be distressing for parents. Yet, unsurprisingly, people on Mom's side of the family think the baby looks exactly like her while people on Dad's side of the family think the baby looks just like him.

The best way to handle insensitive comments about who your child most resembles is to let it roll off your back. Just smile and change the subject.

But if you are not one to let things slide, the next option is to make a joke. You could say something like, "You are right, but she has my charming personality." Or you could say something self-deprecating like, "Thank goodness he looks nothing like me." You could even say, "Yep, I am still waiting to see how my 50 percent of the DNA shows up."

The key is to recognize that most of the time people just feel a need to draw a comparison. It really has nothing to do with you and more to do with them, especially if they are family. They want to find a connection to the baby. Most of the time, they are not trying to make you feel insignificant.

But if the fact that your child looks nothing like you bothers you, start looking for other traits that the two of you share. Maybe your baby makes the same facial expressions you do when concentrating. Or, perhaps your toddler shares your love for pickles. The key is to recognize that you do not have to look like your children to share a bond.

A Word From Verywell

Regardless of what your baby looks like, he or she is a part of you and shares 50 percent of your DNA. So, don't worry too much about the physical traits your baby inherited. After all, these characteristics can change over time. Instead, enjoy time together with your little miracle.

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Article Sources

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