In addition to eye color, another of the first things parents look at as soon as their child is born is the baby’s hair color. It is a physical aspect of the child closely related to the color of his eyes and like this, it is possible that it changes over time.
The baby’s hair color is solely determined by the genes inherited from the father and the mother. It is genetic inheritance that defines, at the moment of being conceived, whether the child will be blond, brown, brown or red.
As I said before, both the color and the quantity and density of hair can change radically during the first months of life. It will only be around a year and a half or two when the baby’s hair acquires its final appearance.
Why does the baby’s hair color change?
What happens in the baby is that there is a physiological shedding of hair . The prenatal hair with which it is born falls out in the first months of life and a new one grows. Sometimes the color with which he was born is the same as the new hair, but in others the new hair is of another color and that is why it is said that the baby’s hair color has changed. What has changed is his hair, which is a different color .
The cells responsible for coloring hair are melanocytes, which produce melanin, which also color the skin and the iris of the eyes. These cells are still immature in the baby and as the child grows, the cells mature and give the hair color. That is why children’s hair darkens with age.
Hair color will be defined by genetic inheritance and depends on the presence of two types of melanin: eumelanins, responsible for dark, black, brown hair, and pheomelanins, blonde and reddish hair. The combination of both results in the natural color of the hair. A higher concentration of eumelanin will give the hair a darker color while a lower concentration will give a lighter color.
When the baby’s hair color changes
As we said above, the hair with which the baby is born is not the final one. It falls off during the first months of life. Sometimes it falls imperceptibly and sometimes in tufts, by areas, being the part that is exposed to more friction where it falls first. Definitive hair begins to grow at around six months, although density and color may still vary. The speed of the molt is variable, it can last months or sometimes exceed a year.
It is approximately a year and a half when the hair color will be the closest to what it will have until puberty , when a new physiological molt occurs, although it will surely darken little by little during childhood
The baby can be born with dark hair, it falls out and is then replaced by the definitive, blond hair. In fact, it’s what happened to my baby. She was born with very little brown hair that has been falling out and now, about to turn six months old, fine blonde hair is showing, which will be the definitive one but will surely darken with age.
The laws of genetics and hair color
As in the case of eye color, the laws of genetics rule. Mendel’s laws, a set of rules based on genetic transmission from parents to children, determine the hair color that the baby will have from genetic inheritance.
Dark hair is dominant over light hair . That is, hair color is the result of a combination of two pairs of genes (one from each parent). For example: if daddy has brown hair (AA dominant) and mommy blonde (aa recessive) the baby most likely has brown hair. This assuming that both have a pure inheritance from both parents, because if there is a blonde allele in the father, it is possible that the baby inherits it and has blonde hair.
Another non-red / red gene pair determined by pheomelanin is also believed to influence a baby’s hair color. In this case, the non-red color is dominant and the red recessive. If the baby has two copies of the red allele, it will be red-haired, a very rare combination.
The combination of these two pairs of genes results in human hair color in all its variants. That explains why there are, for example, blonde and brown colors of such different shades.
As we said also in the case of eye color, genetics is unpredictable, so even if we make calculations about the hair color that the baby will have, it will not be until after six months and more likely towards the first year of life when we can know its final color , although it will probably later darken over the years.
Photo | Caio Resende from Pexels
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