The bottom line is that “everyone’s life experience is different — and that is from the get-go,” Leah Burke said.
Even wars come to an end but sibling rivalry is for a lifetime. This rivalry stems from the contrasting personalities of siblings. Kids born to the same parents can be poles apart. Physician and author Gabor Mate famously said in an interview, "no two children are born to the same parents." Parents are at different stages in their lives when their children are born and have different responses to each child. This leads to shaping different personalities and according to the Washington Post, here is the science behind this.
A child inherits 50 percent of the DNA from each parent, the DNA varies from child to child because it is rearranged during the reproductive process, according to Leah Burke, a pediatric geneticist and chair of the American Academy of Pediatrics Council of Genetics. In an egg cell or the sperm cell, the cell contains a mixture of the DNA the parents inherited from their own parents and it’s a different assortment every time.
The variance between siblings is also a result of epigenetics at work, according to John Pappas, director of clinical genetics services at Hassenfeld Children’s Hospital at NYU Langone. It involves factors such as diet, environmental pollutants, and stress that can affect the ways genes are expressed. Factors such as prenatal exposure to alcohol or being born prematurely can “temper the genetics by quite a bit,” Burke said.
A 2004 study led by Avshalom Caspi, a professor of psychology and neuroscience at Duke University, found that differences in a mother's emotions toward 5-year-old identical twins affected their behavior. In the families, “the child who experienced more warmth, sensitive parenting from their mother displayed less behavioral problems and also had fewer symptoms of depression and anxiety,” said Jasmin Wertz, a psychologist at the University of Edinburgh. The study also found that mothers responded differently to their twin children due to various reasons such as one child suffering from more health problems than the other.
Other areas of parenting that seem to lead to dissimilarities in siblings are cognitive stimulation as children who receive more of it do better academically. Discipline also plays a role in shaping a child. Children who are disciplined more harshly are more likely to develop behavior problems, Wertz said.
Wetz said, “I think it is a big task that you have as a parent, to get to know your child. Sometimes we like the things that are similar in our children to us." But she also added that as parents, one must accept how their children are different from them. The bottom line is that “everyone’s life experience is different — and that is from the get-go,” Burke said. “Giving your children space to be different is just extremely important.”
These are a few reasons why siblings can be so different from each other, as per science.
Cover Image Source: Getty Images | Kevin Dodge