In most cases, allergies are a condition inherited from parent to child. Data shows that the risk of child allergies increases by around 2-4 times if the family tree has a history of allergies. The risk of having a child can be higher if the mother or both parents have allergies. Research shows that children of peanut allergic parents have a seven-fold risk of having the same allergy compared to children whose parents are not allergic to peanuts.
Then if allergies are a genetic condition, will identical twins have the same type of allergy?
Identical twins are not completely identical
Even though identical twins come from the same zygote (the result of fertilizing one sperm and one egg) and eventually split in two, identical twins are not entirely the same in every way. Of course they still have the same sex, the same blood type, and physically it looks almost like a photocopy.
However, the genetic chain is not entirely stable. Genetic mutations can occur at any time, even during pregnancy, and this can be affected by many different things. Therefore, when zygotes divide, some characteristics of identical twins can sometimes also be different.
Even genetic changes continue as they grow due to different environmental exposure factors. This means that even if you and your twin siblings are identical, you can genetically differ as you age.
In addition, there is also a variant of the number of copies, which is when a particular gene in the genome (the total content of DNA in cells) has more than two copies of the gene. In variants of the number of copies, certain genes may have more than 14 copies of different genes.
This results in the possibility of different genetic expressions. The variant number of copies can explain why some identical twins do not have the same properties.
Are allergies in identical twins always the same?
The answer is not always. Identical twins do share the same DNA sequence, so they are more likely to share the same type of allergy compared to fraternal twins. But this does not happen automatically in every case. Even though their genes are identical, it is unlikely that each identical twin has the same type of allergy.
Another study of Mt. Sinai School of Medicine claims that genetic factors account for 81.6 percent of the risk of peanut allergy. This is reinforced by a group of researchers in the UK who said that the allergy was inherited as much as 82 to 87 percent. The researchers also say that when genetic factors are ignored, the percentage drops to 18.99 percent.
Another study looked at 58 pairs of twins, consisting of 44 pairs of fraternal twins (two sperm and two egg cells producing two different embryos) and 14 pairs of identical twins. In each group of twins, at least one of these two people has a history of peanut allergy. All of these twins were observed for signs of an allergic reaction, including itching, coughing, vomiting and diarrhea within sixty minutes after eating peanuts.
The result, in children with fraternal twins, is only 7 percent likely to have the same allergy. While the identical twins are likely to reach 65 percent.
This study also shows that identical twins are more likely to be sensitive to the same allergens. It's just that the symptoms that arise can burst in different ways. For example, when a child has a skin rash when his peanut allergy recurs, his twin has respiratory problems (shortness of breath or coughing).
The difference in these symptoms is also influenced by many things. One of them is how the body's immune system works and its sensitivity to allergen exposure (allergic triggers). The immune system of each twin will develop and react in different ways, especially in the early years.
The important thing you know is that genetics and the environment are both potentially the main factors in causing allergies.
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