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Why are identical twins more likely than fraternal twins to share schizophrenia symptoms?

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Four kittens with different fur patterns-three tabby and one black-and-white-lying together in a box, illustrating genetic variation among offspring. — heredity Each offspring is a combination of its two parents, receiving some dominant traits from its mother and others from its father.

Identical twins are more likely than fraternal twins to share symptoms of schizophrenia because of their higher degree of genetic similarity.

Identical (monozygotic) twins develop from a single fertilized egg and are genetically identical, effectively acting as clones of one another. In contrast, fraternal (dizygotic) twins develop from two separate eggs and share only about 50 percent of their genetic material, similar to any other pair of siblings.12

Research indicates that schizophrenia has a strong hereditary component, meaning the disorder develops more easily in certain genotypes. Because identical twins share 100 percent of their genes, they exhibit a much higher rate of concordance—the probability that both twins will develop the disorder—compared to fraternal twins. While environmental factors also play a significant role in the expression of the trait, the significantly higher concordance rate in identical twins provides clear evidence of a genetic predisposition to the condition.321