14 Analysis of Strange Phenomena in Inheritance

In real life, ordinary people often have a little knowledge of kinship. "I don't look like my parents. It won't be someone else's, will it? " "I am type A blood, and you are type B blood. How can our child be type O blood?" These specious questions are stuck in my heart, and when they are a little noisy, I can't help but leave my wife and children to do paternity tests. In fact, as long as you know more about genetics, you won't make any ridiculous jokes.

14 Analysis of Strange Phenomena in Inheritance

Question 1: unlike father or mother, whose baby is this child?

Positive solution: Just because a child doesn't look like a father or a mother doesn't mean that the child is not his own. The inheritance of human appearance, height, personality and intelligence is not only controlled by polygenes, but also influenced by non-genetic environmental factors.

There are two main types of human genetic characteristics: one is the genetic characteristics determined by a pair of alleles, which are called single-gene genetic characteristics such as blood type and DNA polymorphism. Father and mother pass on one of their genes to their offspring, forming the genotype of the child. Once formed, it will not change. The other is complex genetic characteristics, such as height, fat, skin color, IQ, personality, behavior, appearance and so on. These genetic characteristics are formed by the interaction of multiple pairs of genes and environmental conditions. The role of each pair of genes is tiny, and the interaction of multiple pairs of genes determines the characteristics of individuals. In the process of meiosis of * * * and mature eggs, genes located on different chromosomes are randomly combined, so the genes obtained by brothers and sisters can be different and have different appearances. In addition, complex genetic characteristics are greatly influenced by the environment, such as height and weight, which are directly related to acquired factors such as living environment, nutritional status and living habits. IQ is related to education.

Question 2: Can black Li Kui jy give birth to Snow White?

Truth: Yes. The inheritance of human skin color is controlled by more than two pairs of genes. Genes with different skin colors have the same influence on offspring, and there is no obvious or hidden difference. Therefore, if the father's skin color is dark and the mother's skin color is white, then the child will get a "neutral" skin color. When people of the same race get married, there is little difference in the skin color of their offspring. If a white man marries a black man, the offspring will be gray-black.

Question 3: Both parents are type A, will the baby be type O?

Truth: Yes. Most people know that human ABO blood group system has four blood groups: O, A, B and AB. In fact, these four blood types are all phenotypes. There are six genotypes: 00, AO, AA, B0, BB, AB, so they are all used to detect type A blood. The genotype can be AA or AO, and the same is true for type B blood. Because of this, those so-called A-type parents may not be AA, but AO, so when both parents carry O-type genetic factors, the child is O-type blood. In addition, a person's blood type may not remain unchanged for life. Cancer, blood transfusion, medication and radiotherapy will change his blood type for a short time, and it will return to its original state after a period of time. Children with leukemia and aplastic anemia can permanently become the same blood type as donors after bone marrow transplantation. In addition, because humans have not fully understood blood types, it is found that very few cases will "violate" the above genetic laws.

Question 4: When I was a child, my nose was very short. Is it possible to become a high nose when you grow up?

Of course it's possible. This is the interesting thing about nose inheritance. The genetic influence of the nose will continue into adulthood. Of course, in order to have a straight, tall and narrow nose, parents must have small nostrils and a narrow nose, and at least one nose is straight.

Question 5: My father has black eyes and my mother has blue eyes. What color are the baby's eyes?

The inheritance of eyeball color follows the principle of "black is equal in depth and light color is dominant inheritance". In other words, if you want your baby to have blue eyes, even if you choose a lover with blue eyes, because you have black eyes, the chances of your baby having blue eyes are very small.

Question 6: Can myopia and hyperopia be inherited?

There is a certain relationship between the baby's myopia and heredity, especially if both parents are highly myopic, the baby will be more prone to myopia. Even if you are not born with myopia, you will become a carrier of myopia genes. Once affected by the environment, it may develop into myopia. However, according to relevant data, only 5% of the total number of people are nearsighted because of genetic factors, which shows that the influence of acquired environment and habits can not be ignored. In addition, hyperopia is also related to heredity.

Question 7: Can baldness be inherited?

Baldness is hereditary, male baby is dominant and female baby is recessive. In a word, baldness is passed down from generation to generation. If the father is bald and the grandfather is bald, the incidence of male baby is about100%; If the father is not bald and the grandfather is bald, the male baby has a 25% chance; If the father is not bald, grandpa's hair is thick, and the possibility of baby baldness is almost zero.

In addition, baldness is also closely related to heredity. If the father is bald, the baby is probably bald.

Question 8: If the father is short, will the baby be short?

"My mother is short and my father is short and short." This statement is actually a misinformation. Height belongs to polygenic inheritance. The factors that determine height are 35% from father, 35% from mother, and the remaining 30% are related to nutrition and exercise.

Question 9: Is there a relationship between body shape and heredity?

Body shape also belongs to polygenic inheritance. According to statistics, parents are thin, and babies are mostly thin, and only 7% will be fat; One parent is obese, and the baby is 40% obese; Both parents are obese, and the baby is 80% obese. Obese people often have a family history, but environmental factors also have a great influence on their body shape. After birth, living conditions, nutrition, exercise, work nature and other factors have an impact on its body shape.

Question 10: Who will the skin color of mixed-race children look like?

People's skin color is also polygenic inheritance, and different skin color genes have the same influence on their offspring, that is, when two people with different skin colors get married, the skin color of their hybrid offspring presents the middle type of their parents' skin color.

Question 1 1: Why do some twins look alike, but they are very different?

Twins can be divided into identical twins and fraternal twins. The so-called identical twins refer to the way that only one egg cell is fertilized, and the two cells formed after the fertilized egg divides for the first time develop into two embryos. Because the two fetuses come from the same fertilized egg, the genetic material is exactly the same, so the gender is exactly the same, and the genetic characteristics and performance characteristics are almost the same, so their looks are particularly similar. These twins are also called monozygotic twins. On the contrary, fraternal twins refer to the way that two mature eggs are fertilized with two * * * to form two fertilized eggs, and each fertilized egg develops into a complete embryo. Because these twins come from two different fertilized eggs, their sex may be the same or different, and their genetic characteristics and performance characteristics are very different.

Question 12: Can personality be inherited?

As the saying goes, "Like father, like son", babies are similar in personality and inherited from their parents. But it is also related to the cultivation of the day after tomorrow. As Pavlov said: "Personality is the alloy of nature and offspring, inherited by ancestors, and constantly changing and improving in real life."

Question 13: Will longevity be inherited?

Longevity belongs to polygenic inheritance, which not only involves multiple genes, but also is influenced by diet, exercise and environment. There are two genetic characteristics of longevity: first, longevity can last for many generations, even two generations; The second is maternal genetic advantage, which means that women live longer than men.

Question 14: Is intelligence related to heredity?