How often can we hear from future parents a phrase-question: “I wonder who our baby will look like?” Maybe he will have eyes like a dad’s, and lips like a mom’s? ” Usually, future parents do not rely on the basics of genetics when they ask such questions, although it is they that affect the similarity of the child with one of the adults. Thanks to heredity, babies become like parents, but never look like their complete copies. This is influenced by the multiplicity and diversity of genes.
As soon as the baby is born, the parents immediately try to determine who he looks like, but it's too early to do it. Yes, he may already have some dominant trait inherited from one or both parents, but at this age the kids change very quickly and acquire the features of either one or the other parent, they gradually manifest recessive and dominant traits inherent in each. What are the dominant features of man?
Each person has 46 chromosomes that arise when the germ cells completely merge. These chromosomes contain genetic information from each of the parents, it becomes the basis of the future organism. The process of forming the genetic basis is very complicated, during it, in simple terms, all the parental characteristics are not only summarized, but then also divided equally. So whether your baby will have eyes like that of mom or dad depends more on the case. This is where it is worth recalling the concept of a dominant feature. From the school biology course, everyone knows that genes are divided into strong and weak. During their confrontation, a certain combination of signs is obtained.
The dominant features of a person include: dark eyes and hair, large nose, full lips. In simple terms, everything dark and large will prevail over light and small. That is, if dad has brown eyes, and mom has blue eyes, then most likely the child will inherit the color of his eyes from his father. But do not forget that recessive and dominant signs are not one hundred percent indicators of future appearance. So, for example, if both parents have brown eyes, the child's eyes may be blue. Moreover, according to the laws of genetics, the manifestation of recessive signs is observed in 25% of cases. In addition to the fact that there is a dominant trait, there is also heredity, which also affects the formation of the appearance of the child. Further, in adulthood, appearance will already be determined not only by a genetic predisposition, but also by external factors of a person: nutrition, lifestyle.
If you try to trace how a dominant trait is inherited in several generations, you can see that there is a certain pattern in its manifestation - in each generation this trait will be traced and must be present at one of the parents. Subsequently, it will appear in half of the babies born. And if we talk about a recessive trait - it will manifest itself in one generation, when analyzing several, and the number of children with whom it will be observed will be only a quarter.
Unfortunately, there are pathological hereditary signs that manifest themselves as a disease and can also be transmitted from parents to children as dominant. But due to mutations, these pathological signs can be completely excluded from the gene chain, which will lead to the disappearance of “sick” genetic signs, and the child will not find a disease that has persecuted all relatives for many generations. In this case, the average frequency of all hereditary ailments still remains constant. This is due to the fact that due to the mixing of populations associated with population migration, the set of genes of each person is constantly updated. Along with the update, a mutation also occurs.