The dangers of intermarriage are now well known to everyone, but a century ago, before Mendel discovered the law of genetic combinations, people did not take it for granted.
Instead, he felt that this would make the entire blood-related family more intimate, and also ensure that the blood of his family was pure and not "polluted" by foreign blood.
Intermarriage between close relatives on a relatively large scale in human history generally occurs in large families with certain social status and wealth, especially the royal family and nobles.
Because only they feel that their family's bloodline is relatively good, if the poor have the heart to consider this problem, it is good to get a wife.
Although the royal family in ancient China did not understand the harm of intermarriage between close relatives, nor did they know what genes were, they often accepted the marriage of women from some high-ranking and noble families to the royal family;
This injects fresh blood into the royal bloodline, avoids genetic diseases caused by close relatives, and provides a guarantee for the continuation of the entire family.
Therefore, in ancient China, there were no examples of the collapse of the entire dynasty due to family diseases or extinctions.
However, in the European royal family, their close-in marriage has been interpreted to the point of pure fire. Before the 19th century, europe prevailed in the "politics of the marriage bed", and there was nothing that a marriage could not solve.
Frequent intermarriage between the royal families of various countries has led to a very complicated relationship between them, and they are all relatives. At first, it was certainly not a big problem, but the problem of high genetic similarity could not be avoided after a long intermarriage.
Queen Victoria of the United Kingdom can be regarded as the grandmother of the European royal family, and she also brought hemophilia to the entire European royal family, so hemophilia is also known as "royal disease".
This is not a big deal, after all, the royal families of the entire European countries are intermarried, the personnel base is still relatively large, and there is no serious irreversible harm.
But the Habsburgs, who ruled Spain in the 16th century, were not so lucky, because during the 184 years of the Existence of the Habsburgs, they were all intermarried within their own families, there was no foreign blood, and 9 of the 11 couples were closer to each other.
The final result is that the entire family does not last for several generations, and the continuous intermarriage of close relatives has led to their genes becoming more and more pure, and many genetic diseases have appeared;
The appearance of the faces of the entire family members has also changed dramatically, most notably because each of them has a particularly prominent, long and pointed jaw, which is what we now call the "net red awl face", which was called the "Habsburg jaw" at that time.
By the time Of Carlos II, he was the last and only male of the Habsburg dynasty, so Carlos II was the "integrator" of their family's genetic diseases, the most extreme of which was the loss of fertility due to intermarriage between close relatives.
The entire dynasty was thus overthrown. Here's Carlos II:
He died in 1700 and lived only 39 years, which was also the time of the fall of the Habsburg dynasty, and there was really no successor. From his appearance, he not only has a "ground-wrapped" chin, but also a severe hook nose and hump nose, as well as thick outward-turned large lips.
If it is only a genetic disease on the appearance, it is nothing, ugly and lifeless, but his tongue is unusually fat, filling the entire mouth, causing him to be unable to speak clearly, and all day long it is a harrah, and there is no king's style.
Not only that, but Carlos II was born differently from a normal child, learning to walk at the age of four and speaking at the age of eight, and no one could understand what he was saying, and he often had convulsions.
He also married two wives in this difficult situation, but it is said that he had serious early writing problems that you can't imagine, so he didn't leave any descendants.
So his death may be a relief for him. Here is Carlos II's father:
It is clear that Carlos II inherited the characteristics of his father Philip IV, his mother Mariana was his father's niece, and you now have a relationship between Carlos II and his father and mother.
The answer is that he (the nephew) can also call his father Grandpa and his (cousin)'s own mother his sister.
This relationship is really strange, I dare not imagine.
Look at the following figure:
From left to right, Carlos II called them Grandpa (Philip III) and Grandmother (Philip II), and both of their wives were strongly related to them, but it was clear that their appearance seemed to be slightly more normal, but they could still see the unusually prominent chin.
You might be wondering if they don't realize the dangers of marriage between close relatives? In fact, there is really no, not only do they not have them proud of their protruding chins, because they think that this is a symbol of the royal family, a unique feature of their family, you ordinary people do not have.
And the purpose of their marriage to their close relatives is actually very simple, that is, to keep the throne, and no matter who ascends to the throne in the future, everyone is their own person and a family.
If an outsider enters the family, then the throne is not sure who it is, and intermarriage within one's own family can effectively prevent outsiders from invading their dynasty.
In fact, the reason for this strange idea is related to the history of the Habsburg family. You see, the change of ancient dynasties in our country was basically promoted through war. There is nothing that a fight cannot solve.
But unlike in Europe, as mentioned above, in addition to war, marriage politics is also quite important.
The Habsburgs were initially not related to Spain, and they effectively controlled some parts of Austria, but Philip I of the Habsburgs (who was carlos V's father) married Joanna of the Spanish kingdom of Castile in 1496;
The heroine was the de facto heir to much of Spain at the time, and Philip I became the ruler of the Kingdom of Castile in 1506 after more than 10 years of political competition through Joanna's springboard.
In 1516, Carlos V, the son of Philip I, succeeded to the throne and changed dynasties, beginning Habsburg rule over Spain.
Carlos V, well aware of how his father had opportunistically ascended to the throne, decided to implement strict intermarriage within his family in order to preserve the dynasty, but his dynasty collapsed in just 186 years.
The picture below is Carlos V:
He was the father of Philip II, but from his appearance, the Habsburgs already had a typical "shoehorn face" when they ruled Spain.
It is said that when Carlos V was passing by the streets of Spain, someone shouted at him: My dear king, please shut your mouth, there are many flies in Spain.
It was enough to see that Carlos V could not naturally close his mouth because of his protruding chin.
This is the danger of intermarriage, and although we now recognize this problem, humans often breed other species through inbreeding to make their genes more pure.
This approach is called backcrossing in biology, where the offspring and parental generations continue to hybridize to achieve more prominent trait manifestations. The most common example is the thoroughbred dog we know.
Although they have gained popularity on the outside and have many traits that seem cute to humans, they are also plagued by genetic diseases like the Habsburgs.