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Fascinating Facts the World Knows Thanks to Twin Studies
Contrary to popular belief that eating disorders are only a result of societal pressures, it has since been revealed that there is a strong genetic component. Shutterstock

4. Twin studies are a helpful tool in behavioral genetics and understanding the complexity of eating disorders. 

By studying twins, researchers can vary family environments and differ in genetic makeup. By comparing twins, scientists can better understand the roles of a shared environment, the impact of genetics, and possible unique environments that influence behavioral traits. Research findings from twin studies on eating disorders have found significant genetic components, including behaviors and attitudes associated with clinical eating pathology. One twin study investigated the ‘thin-ideal internalization’ to determine if genetic factors make individuals more susceptible to this outside pressure than others. Sets of twins were studied and evaluated. When one twin has a disease, the other twin’s chances of having it is called the concordance rate. 

The results showed that identical pairs had a closer level of a thin idealization than fraternal twin pairs. The concordance rate for identical twins was 59 percent compared to only 11 percent for fraternal twins. The exciting findings allowed researchers to determine that genetics play a significant role in this area. It is suspected that several susceptibility genes can contribute to an individual’s risk of an eating disorder. The search for specific genetic factors is still underway. 

Fascinating Facts the World Knows Thanks to Twin Studies
Like most human behavior, intelligence is a complex trait that is influenced by genetic and environmental factors. Shutterstock

3. Intelligence can be challenging to study because it is measured and defined in different ways. According to twin studies, intelligence is in your genes. 

Most of the definitions of intelligence include the ability to learn from experiences and adapt to changing environments. Elements of intelligence include the ability to plan, reason, solve problems, and think critically. Many studies rely on a measure of intelligence called the intelligence quotient, or IQ. Researchers have conducted many studies to look for genes that influence intelligence. Many look at the similarities and differences in IQ within families. These studies suggest that genetic factors contribute to about 50 percent of the difference in intelligence among individuals.

By studying both identical and fraternal twins, researchers found that certain brain regions were highly heritable. That included language areas and the frontal region, which plays a large role in cognition. These specific areas showed a 95 to 100 percent correlation between one twin and the other in identical twins. The frontal structure appears to be highly influenced by genes. Fraternal twins were near identical in the language areas but were less similar in other areas. The studies suggest that the environment, their own experiences, and what they learned in life play a negligible role in shaping their intelligence. 

Fascinating Facts the World Knows Thanks to Twin Studies
While mathematics and reading ability are known to run in families, the complex system of genes affecting these traits is largely unknown. Shutterstock

2. Up to 75 percent of differences in children’s abilities in math, reading, and spelling could be due to genetic differences. 

Twins and unrelated children were tested for reading comprehension and fluency. They then answered mathematics questions based on the national curriculum. The information collected as a result of these tests was combined with DNA data and showed a substantial overlap in the genetic variants that influence mathematics and reading. First, the similarities of thousands of twins were reviewed, and measured their tiny differences in DNA. Similar collections of subtle DNA differences are essential for math and reading. 

However, it would be best if you also were mindful that our life experiences are crucial in making us better at one or the other. That is the complex combination of nature and nurture as we grow up to shape whom we become. Although the study does not point to specific genes, it does suggest that genetics influence complex traits such as learning abilities. Children differ genetically in how easy or difficult they find learning. Furthermore, it is crucial not only to recognize but respect these individual differences. Even though the twin studies found such strong genetic influences does not mean anything can be done to assist if a child finds learning difficult. It may just mean that more effort is needed from schools, parents, and teachers to help bring the child up to speed.

Fascinating Facts the World Knows Thanks to Twin Studies
Numerous twin studies have been conducted in an attempt to clear the importance of genes in sexual orientation. Shutterstock

1. Through recent twin studies, researchers have been able to conclude that sexual orientation is genetically influenced.

Some people claim that sexual orientation is a choice or that being gay is a conscious decision individuals make. To determine the role of genetics, if any, in sexual orientation, researchers compared identical twins to fraternal twins. The 2001 review concluded that almost all identical twins were increasingly more likely to share a sexual orientation. That means that they are both either gay or straight compared to fraternal twins, who are genetically less close. These findings suggest that genes do play a factor in a person’s sexual orientation

Other studies have indicated that biological effects, including hormone exposure in the womb, contribute to shaping sexual orientation. These studies support that the differences in the central nervous system exist between heterosexual and homosexual individuals and that the differences are possibly related to early factors in brain development. There are also findings of physiological differences such as different inner ear shapes between homosexual and heterosexual women that contribute to the idea that biological effects play a role. These studies have been able to debunk the myth that sexual orientation is merely a choice. Instead, it relies heavily on genetic factors.