One of the most common questions expectant parents have is what their baby will look like. From the moment pregnancy begins, many people imagine which features their little one might inherit and who they may resemble. While some babies strongly resemble one parent, others arrive with features no one expected.

Some babies look exactly like one parent, while others seem to inherit features from grandparents, siblings, or relatives several generations back. Genetics can work in surprising ways.

Although no one can predict exactly how a baby will look, several factors can influence a baby’s appearance and development before birth. Below, we explore some of the most common influences, from genetics and family history to certain lifestyle factors during pregnancy.

What Determines What a Baby Looks Like?

While many parents wonder whether their baby will inherit Mom’s eyes, Dad’s smile, or a grandparent’s curly hair, genetics play the biggest role in determining appearance. Traits such as eye color, hair color, facial features, height, and body type are all influenced by inherited genes.

However, family history, inherited traits, and certain factors during pregnancy can also influence a baby’s growth and development. That’s why some babies strongly resemble one parent, while others surprise everyone by looking more like another relative.

Although no one can predict exactly what a baby will look like, understanding these influences can help explain why babies often resemble some family members more than others.

7 Factors That Influence Your Baby’s Appearance

While genetics play a major role, a combination of inherited traits and pregnancy-related factors can influence a baby’s appearance at birth.

1. DNA

Everyone knows that DNA determines your baby’s appearance. But DNA is a complex subject. Everything from hair color, eye color, and sex to height and weight can be dictated by your DNA and/or your partner’s DNA.⁹ In most cases, dominant genes are more likely to influence visible traits. However, recessive genes can sometimes appear unexpectedly, which helps explain why babies occasionally resemble grandparents or other relatives more than their parents.¹

2. Alcohol

Drinking alcohol during pregnancy can increase the risk of fetal alcohol spectrum disorders, which may affect a baby’s facial features, growth, and development.^2,3 These conditions can result in characteristic facial differences, such as small eyes or thin lips, and may also impact a child’s cognitive, behavioral, and developmental abilities.^3,10,11

3. Healthy Lifestyle Habits

Moms who make poor exercise and food choices while pregnant may affect whether their child will be born at a healthy weight. Studies show that obese moms are more likely to give birth to babies who later also become obese.⁴ From the moment you realize you’re pregnant (and even before!), make sure you are making healthy, nutritious food choices. Regular physical activity, when approved by your healthcare provider, can also support a healthy pregnancy.

Related: Pregnancy Diet: What To Eat for a Healthy Pregnancy

4. Supplements

Prenatal vitamins are essential for several reasons. However, one supplement, in particular, can play an important role in fetal development more than others. Folate is critical for forming your baby’s spine.⁵ A folate deficiency can result in spina bifida.¹²

5. Caffeine

Studies have shown that excessive caffeine consumption during pregnancy may affect a baby’s birth weight, producing a smaller newborn than usual at birth. Limiting your caffeine consumption to the equivalent of one cup of coffee a day or less is best.⁶

Related: Coffee During Pregnancy: Myths and Facts

6. Environmental Exposures During Pregnancy

While genetics play the biggest role in determining a baby’s appearance, certain factors during pregnancy can also affect how a baby grows and develops before birth. One example is radiation exposure associated with frequent air travel.

Extensive airline travel can expose a pregnant person to small amounts of radiation. While radiation exposure is not recommended during fetal development, occasional travel during pregnancy is generally considered safe for most women.⁷

Related: Flying While Pregnant: 5 Tips and Tricks

7. Family History

Your family history can influence everything from eye color and hair texture to facial features and body type. Some inherited traits can remain hidden for generations before unexpectedly appearing in a child, which is why babies sometimes resemble grandparents, aunts, uncles, or other relatives more than their parents.⁸

You may not know exactly what your baby will look like until the big day, but that’s part of the excitement of parenthood. Whether they resemble you, your partner, or a blend of both, your baby’s appearance will be uniquely their own. Watching those features emerge and change over time is one of the many joys of raising a child.