What will your baby look like? This might be the first question that comes to mind once your pregnancy has been confirmed. There are, after all, many genetic traits to think about.
From hair, eyes, and body characteristics to psychological traits and more, your baby’s looks and personality will remain a mystery as they develop in the womb.
The part of human cells that’s responsible for the way various traits are inherited is called DNA. It’s the collection of all genes that get mixed when a new baby is conceived.
The human DNA (think of it as some sort of genetic currency) is organized into shapes you may have seen in drawings and photos called chromosomes. They resemble a somewhat wobbly letter X. Each person has 46 in total.
Your baby will inherit 46 chromosomes, 23 from each parent. One pair is the sex chromosomes, known as the X and Y. They will determine the sex of your baby.
The mix of genes present on chromosomes, approximately 30,000 of them, will, for example, determine:
- the color of your baby’s eyes
- body shape
- presence or lack of dimples
- a great singing voice
You’re right in thinking that 30,000 genes or more is a lot of material to mix and match. Countless combinations are possible, which is why it’s not always easy to predict exactly what your baby will look like.
Still, because of how genes work, it’s possible to make predictions that are somewhat accurate. It’s a fun game to play while expecting.
Hair and eye color are each determined by a set of genes that dictate the combination of pigment. This can make the hair, eyes, and skin lighter or darker.
Start with family photo albums from both parents. There you can see what hair color is predominant, whether baldness skipped a generation, and if blue eyes showed up occasionally to brown-eyed parents.
While the end result is impossible to guess accurately, here’s some help to understand how genetics works.
There are usually two versions for each gene: one strong (in genetics it’s called dominant) and a weak one (called recessive). Your baby inherits genes from both parents. Some of them will be dominant and some recessive. How does that apply to eye color?
For example, if you have brown eyes and mostly everyone in your family has brown eyes, that points to a strong or dominant version of a brown eye color gene or set of genes. Suppose the other parent has blue eyes and his or her extended family does, too. Your baby will likely have brown eyes because that color is usually dominant.
The blue eye genes will not be lost, though. They can manifest down the road in your grandchildren, should a certain mix of genes from parents occur.
In the same way, if both you and your partner have brown eyes but have had blue-eyed ancestors (check the family album!), your baby might have blue eyes because each of you have some blue eye genes that you carry in your DNA.
Strong or dominant genes determine your baby’s hair color, too. There are two types of melanin pigment in hair that, depending on which genes are stronger, mix up and determine the color of your baby’s locks.
As your baby grows, you may notice that their hair becomes darker. That’s normal. It has to do with some of the pigment production slowing down.
In general, if you have darker hair, there may be a gene for blond or dark that you carry. So if your partner has a similar combination, two darker-haired people can have a blond or red-haired baby. That’s all part of normal gene play.
In trying to predict characteristics like hair or eyes, you may have to look at skin tones too. Sometimes a person has darker hair and light skin, an indication that there is a chance of having a baby who will sport lighter-colored hair.
Looking at a newborn to see who they look like the most often has people point to the father. Does that mean that babies look more like their fathers than their mothers? Not really.
The most plausible explanation, researchers found, was that centuries ago, the baby-dad resemblance meant that the new dad would have more incentive to provide for mom and baby.
Biology and genetics do not work well with subjective opinions, though. Luckily, people now know that babies can look like either parent. But most often, they’re an intricate combination of the two, plus some family traits that have been passed on.
Also, given that many traits skip a generation or even two, you may be seeing more of your grandmother in your baby than you expected. Having the photos handy makes it easier to bring your guesses closer to reality.
One thing you should be aware of is that there are a lot of myths out there about the way various characteristics are inherited. Genes do their own thing, so some combinations can give an unexpected result.
For example, if you and your partner are both tall, there’s a high chance your baby will grow to be a tall person. A difference in height will place your baby in the middle of the height range. The gender contributes to the height, too.
What will your baby look like? It’s a guessing game that has all parents on their toes until the big day comes and they get to gaze at their bundle of joy.
No matter what your expectations were for your baby, once they are born you’ll find yourself madly in love, eye and hair color notwithstanding. Enjoy your baby’s uniqueness, both physically and psychologically. Have fun guessing how genetics have shaped your family!