When a family has a child and friends meet for the first time, the first topic of discussion is often "Who is the child like?" ”
For example, when we gave our daughter a "full moon wine", some relatives and friends met our daughter and told me something like, "This child's eyebrows and eyes are really like her father".
In the folk, daughters are like fathers, sons are like mothers, and this saying seems to be recognized by many people.
It seems that a child's appearance can only be determined by the genes of his parents!
So, is there any scientific basis for the statement that appearance is determined by genes?
Let's find out!
01 Boys are like moms, girls are like dads, are they reliable?
To understand this question, we first need to understand a concept - chromosomes.
Netizens who have studied biology know that there are 23 pairs of chromosomes in the human body, of which 22 pairs are autosomes, and they are the same in both men and women. And the 23rd pair is the sex chromosome, which determines the sex of the child, XY for boys and XX for girls.
For example, the right side of the image below is the chromosome map for boys, and the chromosome map for girls is on the left.
As we can see from the figure above, the Y chromosome is relatively small in size and contains less genetic material than the X chromosome, and scientific research has found that many of the genes that determine male sex are fragments.
The boy's X chromosome comes from his mother's egg, and the Y chromosome comes from his father's sperm.
So, for boys, if the X chromosome carries a dominant gene related to facial features or body structure that is not on the Y chromosome, it will definitely be reflected in the boy.
This is the theoretical basis for "boys are like mothers".
Unlike boys, girls have X sex chromosomes, except that one comes from their mother and one from their father.
Therefore, on the genetic level, girls are almost the same as their parents, and there is no theoretical basis for "girls like dads".
02 What physical traits do parents pass on to their children?
Although genetically speaking, "boys are like moms" is more reliable, in real life, not all boys look like moms.
This is because the genes that affect the appearance of human beings are not inherited and manifested, but also related to the strength of the genes, that is, "dominant genes" and "recessive genes".
Dominant genes are more "strong" than recessive genes, and when we inherit genes from our parents, if there is a dominant gene and a recessive gene, then the dominant gene usually "masks" the effect of the recessive gene, making us exhibit the characteristics of the dominant gene in appearance or characteristics.
For example, in the genetic map of single and double eyelids in the figure below, single eyelid a is recessively inherited, and double eyelid A is dominantly inherited, so the combination of Aa is manifested as "double eyelid".
But if we inherit two recessive genes from our parents, then these recessive genes will only manifest themselves in our appearance or characteristics.
Dominant genes that are susceptible to parental influence in appearance:
(1) Eyes:
Generally speaking, whether the eyes look good or not is mainly affected by the single eyelids, the length of the eyelashes, and the size of the eyes.
Double eyelids, long eyelashes, large eyes, and black pupils, which are the genes that make the eyes look good, are all dominant traits.
Therefore, if the parents have characteristics such as double eyelids, big eyes, and long eyelashes, then the probability that the child has double eyelids, big eyes, and long eyelashes will be greater.
(2) Nose child
As the main part that affects a child's appearance, the nose is not as lucky as the eyes.
Because the big nose tip, wide nose bridge, short nose root, and hooked nose are all dominant traits that make the nose unsightly.
Therefore, if one of the parents has particularly prominent dominant characteristics, such as a large nose tip, a wide nose bridge, etc., it will be easy to pass it on to the next generation.
Of course, as recessive traits, "high-quality nasal features", such as a small nose tip, straight nose bridge, moderate nasal wings, high nasal roots, and rounded nasal tips, are also difficult to collect in a person's nose.
Therefore, the reason why many celebrities are good-looking is because they have a super good-looking nose with all the invisible features of the nose.
(3) Ears
The size of the ears is also hereditary, with "big ears" being dominant and "small ears" being recessive.
So, if one of the parents has big ears, the child has a greater chance of having big ears.
(4) Lower shape
The "wide chin" in the shape of the jaw is dominantly inherited, so if one of the parents has a prominent wide chin, then their child agrees to have the same wide chin.
(5) Drinking cavity
If you look closely, you will find that there are fewer people with "dimples" in their lives, and this is because "no dimples" is dominant inheritance, and "dimples" are recessive inheritance.
Therefore, if only one parent has dimples, it is difficult to pass them on to their children.
(6) Hair
"Curly hair" is the dominant gene, and "straight hair" is the recessive gene, so if one of the parents has curly hair, then the child will have a greater probability of having "little curly hair".
(7) Mouth
Thin upper lip, bulging lower lip, and large mouth are also dominant genes, so if one of the parents has a large mouth, or thin lips and a bulging lower lip, the child will have a greater probability of having a big mouth and thin lips.
03 The acquired environment also affects appearance
According to the above theory, identical twins are genetically identical and should look exactly the same, but in real life, not all identical twins look exactly the same.
For example, in the documentary "Twin Strangers" filmed by B B C, three Chinese triplets with the same genes have differences in facial features and height when they grow up.
The main reason for these discrepancies is that they were adopted by two families in the United States and one in Norway shortly after birth.
It can be seen that a person's appearance is not only determined by genetics, but also closely related to acquired environmental factors.
Some acquired factors that can easily lead to children becoming ugly are shared with you, and I hope that parents can carefully check them and intervene in time.
(1) Bad habits
Long-term breathing through the mouth, sucking fingers, sticking out the tongue, biting the lip, habitually chewing food on one side and other bad habits can lead to lip muscle hypertrophy, crooked teeth, and jaw deformity.
Long-term consumption of high-sugar and high-fat foods may also lead to children's body obesity and skin problems, such as acne and greasy skin, which will affect children's appearance.
In addition, long-term use of the same sleeping position may also affect the shape of the child's skull, which in turn will affect the appearance.
(2) Dental caries and periodontal disease
Teeth play an important supporting role in jaw and facial development.
Multiple tooth decay and periodontal disease can cause your child to be unable to chew food properly, and in the long run, the jaw bone will underdevelop due to the lack of normal physiological stimulation, resulting in facial deformities.
Especially when children have decay on only one side of their teeth, they may develop the habit of chewing laterally, which can lead to asymmetrical facial development and further exacerbate facial deformities.
(3) Poor sitting and walking posture
Poor posture such as hunched back with chest and shrugging when walking not only affects temperament, but may also have an adverse effect on bone development, resulting in poor body shape.
[Written at the end]
Genetically speaking, boys are more likely to be like their mothers, both in appearance and in other aspects; For girls, it's half with mom and dad.
In real life, the reason why some children do not follow the law of "boys like mothers" is mainly because the expression of genes is divided into dominant recessiveness, dominant genes are stronger and have a greater chance of being expressed, and recessive genes are weaker and may not be expressed if inherited.
In addition, it is worth noting that the appearance of children is not only affected by congenital genetics, but also related to factors such as the acquired growth environment and living habits.
Therefore, as a parent, if the child is beautiful when he is a child, but if he grows older and uglier, it may be affected by the acquired environment, and he needs to pay attention to it and correct it in time.