Most people realize that the offspring of inter-family pairings is at a higher risk of problems, but why is that? How does this affect DNA? Why is it important to have babies with people that are different from us? What are the consequences of incest?
It all comes down to gene diversity. Every person has 46 chromosomes that are packed with genes. We're actually made up of two sets of the same 23 chromosomes. We get one set from our mothers and one set from our fathers. Each one of us has two copies of every gene.
Genes change and mutate all the time creating different forms of themselves. These alternative forms of the same gene are called alleles. Some are good, and some are bad. That's why having two sets of genes is important. If one gene is bad, we have a second copy to use as a back up.
Every person has between five and ten defective genes. Most of the time we don't even know about these broken genes that we carry because they don't cause any symptoms. Since genes are passed down through generations, every family has a certain set of these defective genes which vary from one family to the next.
When two people with similar genes produce offspring, the chances of passing on the same defective genes is much higher. In this case there is no good gene to serve as a backup and the disease or condition will manifest itself. Although it is possible to find two unrelated people who happen to have the same defective gene, the odds are much greater among family members.
14 The Jaw Will Not Look Right
Prognathism is the extreme protrusion of the jaw. If the upper jaw protrudes it is called maxillary prognathism and when the lower jaw protrudes it is mandibular prognathism. This is also called The Habsburg Jaw as it was prevalent in the Habsburg bloodline due to inbreeding.
The Habsburg family intermarried to secure their interests. As a result the family courted a number of genetic problems including the Habsburg Jaw. Charles II of Spain had one of the worst cases of this mandibular prognathism as well as being physically and mentally disabled and infertile.
His mother and father were uncle and niece. Charles did not not learn how to speak until age four and couldn't walk until age eight. The extreme deformation of his jaw made it difficult for him to chew or speak. Due to his inability to produce an heir, Charles was the last Habsburg monarch of Spain.
13 One Of Them Won't Descend
Cryptorchidism happens when one or both testicle doesn't descend down into the scrotum. Around 3% of full-term baby boys have this condition, and about 30% of premature baby boys are affected. Most of these instances are not true cryptorchidism as they will resolve themselves within the first year of life. Only about 1% of baby boys will have an actual problem that will require treatment.
Testicles need to descend so that they can regulate temperature and protect the sperm. If they remain inside the body it can cause infertility as sperm is very sensitive to heat. Men with one or both undescended testicles are more likely to develop an inguinal hernia where the intestine is pushed through the abdominal wall. Undescended testicles are also at higher risk of testicular cancer. This is true for both the descended and undescended testicle and the risk remains even once the cryptorchidism is corrected.
12 The Limbs Will Fuse
Although this abnormality sometimes occurs spontaneously, fused limbs seem to be more prevalent in children of incest. Most often the toes or fingers are affected with the skin around the limbs being fused together. In milder cases this can appear as a webbing of skin between the limbs. In more serious cases the fingers or toes can lack definition altogether.
Perhaps the most extreme form of this defect is a condition known as sirenomelia. It is sometimes referred to as mermaid syndrome because the legs are fused together and resemble a mermaid's tail. Unfortunately it is often fatal and usually results in stillbirth as the internal organs tend to be affected.
Fused limbs can sometimes be corrected surgically. In many cases the skin around the limbs can be severed and the limbs will appear and function normally. If the bones, and surrounding tissues are affected surgery can be less effective and in some cases not worth the risk.
11 Something Will Be Clearly Missing
Anonychia congenita is a nail disorder characterized by the absence of, or abnormally developed, fingernails and toenails. The disorder is very rare and is usually due to a mutation of the R-spondin 4 gene which encodes the R-spondin 4 protein that is necessary for the formation of nail tissue. While not life threatening, there is no treatment for anonychia congenital.
This particular genetic mutation is prevalent in the incestuous Kingston family clan. They are a clan of fundamentalist Mormons who practice polygamy. This group of people practices inbreeding to preserve what they believe to be superior genes. Although highly secretive and generally withdrawn from society, several genetic abnormalities, such as anonychia congenital, have been observed within the Kingston family.
10 The Head Will Be Unusually Small
Microcephaly is a serious complication where a child has an unusually small head for their age and gender. Often this is apparent at birth but sometimes the defect becomes more prominent in the first few years of life. Although microcephaly sometimes occurs when a pregnant woman is exposed to certain toxins, viruses, and medications, there are also several genetic mutation which can cause this condition.
The diminished size of the head occurs due to improper development of the brain and depending on the extent of the problem complications can be serious. Possible symptoms include intellectual disability, developmental delays, facial distortion, difficulty with coordination and balance, and seizures. There is no cure for microcephaly, only management of symptoms. Early diagnosis and intervention with developmental issues is the only way to improve quality of life for affected children.
9 Their Growth Will Be Stunted
Dwarfism could be a medical or genetic condition and it applies to any adult who is 4'10” or shorter. It is a broad term and includes many genetic abnormalities that could be the underlying cause of the condition. Although sometimes spontaneous, dwarfism has been linked to incestuous breeding especially when it occurs over multiple generations.
In cases where the dwarfism is caused by issues with hormone productions, the condition can often be corrected with hormone therapy while the child is still growing. Otherwise dwarfism can't be cured. There are many possible complications that can result ranging from skeletal and muscular issues, to developmental delays in babies, or excessive fluid around the brain. It is very important for anyone with this condition to monitor their health carefully so that any problems can be caught early and addressed.
8 They Will Not Be Able To Reproduce
It's almost as if nature has a built in safeguard against inbreeding as the chances of infertility are much higher in the offspring of incest. The viability of both sperm and eggs can be negatively impacted by the increased presence of defective genes and especially in the presence of duplicate recessive genes of improper function. Each generation of incest increases the number of these problematic alleles and makes fertility issues that much more likely.
If conception does occur, the fetus of an incestuous lineage is much more likely to have complications during development and the risk of spontaneous abortion is much higher. The chances of repeated stillbirth is significantly higher as well as early infant death. Inbreeding also raises the risk of premature birth, low birth weight, and complications for both the mother and infant.
7 The Spine Won't Grow Right
Scoliosis happens when the spine shows abnormal curvature from side to side in an “S” or “C” shape. This condition can be caused by a spinal injury or a defect in the skeletal, muscular, or nervous system. Some known causes include cerebral palsy, muscular dystrophy, and spina bifida. Congenital scoliosis results from embryological malformation of one or more vertebrae which causes one area of the spine to lengthen at a slower rate.
Mild cases of scoliosis generally don't impact a person's life but severe cases can affect the ability to walk or sit comfortably. Children with congenital scoliosis are at higher risk of developing problems with the spinal cord, genitals, urinary system, and the heart. Although there is no cure, scoliosis can in some cases be treated with the use of braces or surgical corrections.
6 They Won't Be Able To Fight Off Disease
Inbred people tend to have more health issues than those that come from a diverse gene pool. Some of these problems are due to deformations of bones, muscles, nerves, and organs, but others are the result of an inefficient immune system. An immune system without gene diversity is much less able to fight off a wide range of diseases.
The immune system depends on the Major Histocompatibility Complex region of DNA to identify and destroy the things that can make us sick. The MHC region relies on genes to do it's job and the more versions of a gene it has to work with, the more effective it is at fighting disease. In the narrow gene pool of incest, the same genes are passed down by both parents and duplicate genes are not what the MHC region needs.
5 Their Blood Won't Clot
Hemophilia happens when the blood does not clot properly leading to excessive bleeding. The blood clots by using small cells that form in bone marrow called platelets. A person with hemophilia lacks, or has low levels of, certain proteins called clotting factors. There are 13 types of clotting factors that work with platelets.
Hemophilia is an inherited genetic condition. There is no cure but it can be managed to prevent complications. There are three types of hemophilia (A, B, and C) with A being the most common. Hemophilia C is autosomal and affects males and females equally. Hemophilia A and B are carried on the X chromosome and are more common in males because females have a second X chromosome to counteract the one with the defect. A female would only be affected if she has two defective X chromosomes.
Hemophilia was once known as the Royal Disease because it began to appear in the descendants of Queen Victoria. Incest was common among royal families and likely contributed to the high occurrence of the disease in this bloodline. Modern testing has revealed that the family suffered from the rare hemophilia B.
4 Their Central Nervous System Will Be Attacked
Tay-Sachs disease is a genetic disorder of the central nervous system. A defective gene causes the body to not make a protein called hexosaminidase. Without this protein chemicals called gangliosides build up within the nerve cells in the brain causing brain cells to die. There is no cure for Tay-Sachs.
This disease typically begins before birth and is always fatal. For affected infants life expectancy is 4 or 5 years. Symptoms include deafness, blindness, loss of muscle function, slow growth, delayed development, seizures, and a red spot on the eye. Tay-Sachs can also occur in teens and adults causing less severe symptoms and somewhat longer life expectancy but this is more rare.
Tay-Sachs is hereditary but it is a recessive gene. Two copies of the defective gene need to be present for the disease to manifest itself. If a child is born with only one defective gene they will live a normal life and be a carrier for the disease. Both parents need to be carriers in order for their offspring to have the disease.
3 They Will Have Severe Asymmetry
There are several congenital birth defects that can affect the symmetry of a person's face or body. Although these faulty genes are not limited to the offspring of inbreeding, they are much more likely to manifest themselves in children of incest, and especially after multiple generations of incestuous breeding. There is no cure. Sometimes corrections can be made with surgery but often the risks of surgery outweigh the benefits.
In cases of severe asymmetry some tasks, such as speaking and fine motor skills, may be more difficult but generally people with severe asymmetry can lead long and fulfilling lives. One exception to this is cases that are caused by the genetic defect hemihyperplasia. People with this genetic abnormality have a higher chance of developing tumours and need to be monitored carefully.
2 Their Palate And Lip Won't Be So Pretty
A cleft lip occurs when there is a split in the lip going upwards toward the nose. A cleft palate occurs when the roof of the mouth does not form properly leaving an opening. The palate consists of two parts, the hard palate and the soft palate. The hard palate is the bony part at the front of the roof of the mouth. The soft palate is the softer material at the back. Either one of these can be cleft.
A cleft palate is not always caused by inbreeding. There are several environmental and lifestyle elements that are believed to increase the risk of a baby developing this malformation. However genetics does play a role as well when both parents are carriers for the defect. The only treatment options for a cleft is surgery.
A child with a cleft palate might have feeding issues because the barrier between the mouth and nose is abnormal. This could cause liquids ingested through the mouth to come out of the nose. The cleft also has a tendency to affect the teeth making it more difficult to chew. People with a cleft palate are at greater risk of middle ear infections and issues with the eustachian tubes. In severe cases this could cause hearing loss.
1 Something Will Happen To Their Feet
Clubfoot occurs when the bones of the foot are malformed causing the foot to be turned sharply inward causing the heel to look like it's on the outside of the foot. Children with clubfoot may have a smaller calf on the affected leg and the leg may be a bit shorter. They also tend to walk on the outside edge of the clubfoot and wobble to maintain balance.
This condition may occur as part of a larger skeletal abnormality, or it may be a stand alone problem. A family history of clubfoot increases the likelihood that a child will be affected as well. In cases of inbreeding within a family with the condition, both parents would be contributing the genes that can cause this malformation greatly increasing the risk for their child.
Clubfoot may look painful but it generally doesn't cause discomfort until later in life. While not life threatening, the condition can affect mobility and quality of life. Treatment methods involve stretching, bracing, and surgery depending on the severity of the clubfoot.