Almost everyone has twins around them or more or less, because the odds of twins are not particularly low. However, the birth of twins often has unintended consequences for human beings. For example, a child may be born as the mother of another baby; A new study shows that in cities, the probability of twins being born is about 33%.
You may have met twins that look particularly similar, or you may have encountered twins with slightly different ones, but you may not know that twins can also be black and white.
Above, a pair of twins from the UK, Lucy, fair-skinned, Maria, dark-skinned.
In their own words, no one would think they were twins even if they were wearing the same clothes because their skin tones were so different.
The sisters were born in 1997 to an English, typically white father, but a half-Jamaican black female mother.
Lucy apparently inherited her father's skin, while Maria inherited her mother's skin.
Many people were surprised when their story came to light in 2015.
So, the question is, why are the twins so different? Why are there huge differences between different races? Why are some people born in the United States and others born in Canada? Why did white and black marriages succeed or fail in the same country? Is it possible for a white person to marry a black man and have a white offspring?
We usually refer to this phenomenon as identical twins or synonyms for fraternal.
Twins are sometimes even completely different in gender (we call them dragon and phoenix babies) because there are so many examples of twins, and more commonly, identical twins and fraternal twins.
The question of whether identical twins and heterozygotic daughters can have children is mentioned in the illustration.
Usually the twins we encounter are basically identical twins, but they are developed from fertilized eggs.
During development, the fertilized egg splits into two embryos and eventually develops into two individuals.
In this example, because twins have the same DNA, children after birth will particularly like and 100% like the same sex.
Identical twins have a probability of birth of about 3:30, while fraternal twins have the opposite.
Interestingly, the probability of identical twins is almost the same in all species, although no one yet knows what the mechanism of induction of identical twins is.
Fraternal twins, on the other hand, are genetically determined, and in general, black people have the highest odds of having fraternal twins, at 20%, followed by whites, while Asians have a much lower odds of having fraternal twins.
We know that normally, a woman can only lay one egg at a time, but sometimes she lays more than two eggs, and when the two eggs are fully fertilized, it forms fraternal twins.
After the heteroembranous daughter is born, it cannot develop normally because there are no sperm cells in the egg.
However, if you have a chance to look at these beautiful and lovely women, you will surely find that they all have a common trait - that is, they all have the same name - "Li", and this name also contains some impressive genes - which is why some girls have different genetic factors (such as skin color) than other girls?
If you're wondering what determines their skin color?
Genes that determine skin color
Many people may have noticed that when married to black people, children's skin tends to be darker.
However, if we put this problem on a man, it is that they all have white hair – because they all have a common name , "Leigh", which in turn is related to his or her wife' " home " – so let's take a look at how these people's hair is made before we look at their family portraits!
The photo above is a family portrait of Lucy and Maria, and you'll notice that, with the exception of Lucy, several of the British couple's children have darker skin.
In fact, it is not true that the black offspring I mentioned earlier are generally black is a misconception of racial genetics, because we subconsciously believe that as long as the skin of the black offspring is slightly darker, they are black, especially in the United States, and any generation of intermarriage with blacks in a family will be considered black.
But the truth is that when they marry white people, their skin color changes or becomes lighter, and even directly white.
Skin color is mainly determined by melanin (secondary factors include hemoglobin, etc.), which, like other physical characteristics, is determined by genes.
While the number of cells that produce melanin in each person is similar, the proportion and distribution of melanin varies from person to person, which is why skin color is not based on a single gene.
Polygenic inheritance leads to differences between individuals, and this difference is caused by phenotypic expression. But genetically, we know that this result doesn't hold. Because each species has its own unique chromosomal loci and genotype (the so-called "genomic loci"), and there is no connection between these loci and their phenotype. In fact, at least eight gene sites are known to determine the color of the skin.
The offspring of a black couple also have different skin tones.
The map above is a simplified genetic trait of skin color, and it's not hard to see how complex skin color genetics are.
Genes with high pigmentation and low pigmentation vary greatly between different races. In this series of articles, we introduce two common melanin-forming mechanisms and make a comparative study of different types of cells. This will provide new perspectives for people to better understand and understand the melanoma of humans themselves. Both families have parents of dark skin and low pigmentation genes.
The pictures show that the more pigmentation genes their offspring have, the darker the skin color of their offspring.
But you also notice that when there is only one black spot, the person's skin will also become darker, because
Most of the time, black is the dominant gene.
Interestingly, however, the probability that the pair of dark-skinned parents will have a pure white offspring is one in 64, the one in the upper left corner.
This is a simplified genetic feature of black skin, and the reality is much more complicated, but it is not difficult to see that even two black offspring may be white.
However, if you see a young man at home holding her child, he (or she) will say, "I am that woman..." If you see a young man at home picking up a girl, he (or Ben) will say: 'I'm not that woman...' If you meet a young man at home who picks up a girl, you will say, 'You're white — low pigmentation genes — "If you meet a young man at home with a girl, he will say, "You're Jamaican— white."
White children often answer probability questions by saying, "If I had a fraternal sibling, then I would have to give birth to them all..." This story reminds us of the relationship between siblings.
However, black and white twins like Lucy and Maria are rare, and some experts say there is a one-in-a-million chance.
I don't know how that one in a million came about, but when I was looking for information, I found that the two of them were definitely not the only pair.
I once did a survey: on two occasions the black and white twins were born in the UK.
There is also a couple in the UK (white wives and black husbands) who have even given birth to such "black and white" twins twice in a row.
Now that the trend of globalization is becoming more and more obvious, it is difficult to judge which recessive genes a person carries, a white person may have some dark skin genes, and the same black person may have some white skin genes.
So it's not surprising that whites marry whites and give birth to black offspring (very few), or blacks marry blacks and give birth to white offspring, let alone blacks marry whites and give birth to white offspring.