2023-09-27 15:45:00
Genetic inheritance can determine everything from eye color to a person’s height (Infobae/Archive).
Genes are instructions that cells use to make proteins so they can function. Each person inherits two copies of each gene, one from each parent. This information can present subtle differences, known as alleles, and when they are fused, the genotype emerges whose task is to determine a physical trait. For example, hair texture is shaped by this genetic interaction.
The characteristics that are observed in the appearance of each individual are known as phenotype. In addition to hair, other physical traits are determined by inherited genes: from a person’s height to the color of their eyes, genes combine in different ways in each person, even in members of the same family.
However, some of these physical factors also depend on environmental elements and some practices might even favor the development of a characteristic. For example, height can be influenced by both genes and contextual factors such as nutrition, type of diet, congenital diseases and physical activity.
Genes have two main classifications: dominant and recessive. A dominant gene is one whose variant is expressed even if only one copy is present, while the recessive gene needs two copies to manifest. Not all recessive genes are linked to abnormalities or diseases. Some may be related to completely normal traits, such as eye color. For example, the combination of two recessive genes causes people to have blue eyes.
Blue eyes are the result of two recessive genes (Infobae/File)
A study published in Science Advances identified 50 genes for eye color from analysis of nearly 195,000 people in Europe and Asia. The team of researchers from King’s College London and the Erasmus University Medical Center in Rotterdam assured that the genetic variations in eye color in Asians with different shades of brown are similar to what happens in blue-eyed Europeans. The findings also represent an approach to understanding eye diseases such as pigmentary glaucoma and ocular albinism.
The interaction of specific genes, such as KRTHAP1 and TCHH, plays a role in determining hair structure. The second gene, TCHH, appears to be linked to differences in hair texture in people of northern European ancestry, according to the U.S. National Library of Medicine, but evidence is still lacking to confirm this. While there are different associations of hair types with a given genetic variation, follicles offer a clearer pathway.
Hair might be an evolutionary result to protect people from UV rays (Europa Press)
There is a principle identified in this topic: the follicle that appears perpendicular to the surface of the skin will see straight hair grow. This is because keratin is produced homogeneously in any direction. By having a slightly more symmetrical distribution around the skull, the shape of hair growth will be circular, according to Muy Interesante.
In the opposite case, a person with curly hair has follicles close to the plane parallel to the surface of the scalp. Keratin arises asymmetrically. In this way, hair loss will form ellipses; It will also grow more on one side than the other. The appearance of this type of hair also has anthropological explanations that consider it an evolutionary result to protect people from UV rays and retain heat, according to National Geographic.
In any case, color is defined by several genes, which work together to determine the amount and type of melanin, the pigment that gives hair its color.
Although environmental factors such as general health, diet, and grooming influence hair characteristics, genes provide the underlying foundation that directs these characteristics at a fundamental level.
Height is one of the physical characteristics most closely linked to genetic inheritance. The height that a person might reach in adulthood is determined, to a large extent, by a complex network of genes. In a study published in the scientific journal Nature Genetics, 697 genetic variants related to this trait were identified. However, other environmental elements such as healthy eating and constant activity have an influence, since in some cases people grow more than expected.
Height is almost entirely inherited from the genes of both parents. (Reference image).
Regarding the percentage in which genetic inheritance intervenes in height, it has been studied since 2007. Currently, it is known that 80% of the variability in height is attributed to genes. In addition, the company GIANT (Genetic Investigation of Anthropometric Traits) clarified that there are more than 400 regions of the human genome that are involved in this physical trait, according to the BBC.
Heredity intervenes by regulating the development and growth of bones and tissues in the human body. Genetic variants related to height affect the production and action of growth hormones, as well as the formation of cartilage and bones early in life. However, it is likely that if a baby’s parents are tall, he will also be tall as he matures.
Dimples (indentations in the cheeks) can appear in entire families. Biologists thought they were hereditary traits, but in recent years it has been known that it might be an irregular characteristic. This phenomenon was generally considered a result of dominant genes, meaning that one copy of the altered gene is present in each cell, according to the US National Library of Medicine.
Although the dimples in the cheeks were considered an irregular genetic inheritance, it is known that they are the result of the functioning of several muscles when smiling (Gettyimages).
The appearance of dimples on the cheeks is due to certain facial muscles working in a unique way and creating small depressions in the cheeks when smiling or laughing. Unlike more uniform facial features, they are considered irregular dominant features. The above means that their presence follows an unpredictable genetic inheritance and can arise even if only one of the parents has them.
The earlobe, unlike other physical traits, is the result of a complex dance of genes. Whether a person has this part separated or attached to the face depends on the genetic history of their ancestors, although it has currently been identified that it is the product of the intervention of several genes at the same time.
At least 49 genes are involved just in determining whether a lobe will be separate or separate from the face (Pinterest).
In a study carried out with samples of at least 75,000 participants, scientists carried out a registry in which they explored genetic variations related to the earlobe. The research determined that 49 genes are involved that play an important role in both types of lobes, according to the analysis published in the scientific journal American Journal of Human Genetics.
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