Landmark Research on Siblings May Help Identify Mental Health Risk Factors

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Scientists have studied the concept of “nature versus nurture” for decades.

While each family is unique, it appears that both home environment and genetic factors are vital in predicting our overall health as adults.

But recent studies have provided even more information on just how crucial it is for a child to be raised in a loving and supportive home.

In two separate studies reported in the American Journal of Psychiatry, researchers delved into the “nature versus nurture” dilemma as it pertains to the development of depression and mental health issues as adults.

One study included more than 6,000 subjects in Sweden – pairs of siblings who were biologically related but raised apart, one at home and one by an adoptive family. 

In each case, at least one biological parent had been diagnosed with depression.

The children raised in supportive adoptive family environments where neither parent experienced depression were nearly 25 percent less likely than the sibling raised with their biological parents to develop depression as an adult.

This was the data for full biological siblings, but half-siblings also experienced a marked decrease in the development of depression – around 20 percent less risk than that of the child raised in the biological parent’s home.

Of course, all families and circumstances are unique, and if any sort of trauma like death or divorce occurred, or if one of the adoptive parents was diagnosed with depression, the risks were the same as their sibling’s risk.

But it is an interesting look into just how vital the physical and mental health of parents is to their child’s lifetime well-being.

The research seems to prove there is some kind of protection against the genetic predisposition to depression if the childhood environment is loving and supportive overall.

Millions of adults experience depression, anxiety, and other mental health issues. 

While their children are not always affected, there has been a great deal of research into just how much genetics and environment impact children who have one or more parent with depression.

Kenneth Kendler of Virginia Commonwealth University, one of the lead researchers on the project, says the study is unique in that it examined siblings raised in different environments.

The conclusions drawn are important in finding ways to decrease the risk of psychiatric disorders in high-risk families by providing resources and support to bolster family relationships when children are young.

In a related long-term study appearing in the same journal, data was collected over the course of decades to determine how sibling relationships can affect the development of mental health issues and substance abuse in adults.

Researchers examined the quality of sibling relationships in childhood, the stability of the home environment, and family medical histories in regard to mental health issues and substance abuse.

By and large, when children had a close relationship with their sibling(s) throughout childhood, it appeared to have a more protective effect than even the parent/child relationship.

If sibling relationships were poor during childhood, researchers found that by age 50, one or more children of the family were more likely to experience depression, alcoholism, or drug use.

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This is landmark research because the majority of studies conducted on the risk factors for depression have been based on the parent/child relationship.

By conducting further research on sibling relationships, the medical community hopes to gain a better understanding of what childhood circumstances increase or decrease the risk of depression or substance abuse as adults.

One thing is clear, however. 

While the most important predictor of lifetime mental health is the quality of the parent/child relationship, having a close relationship with siblings seems to give children more confidence and the ability to build healthier interpersonal relationships throughout life.

Even when the parent/child relationship is strong and supportive, a strong sibling relationship can further teach a child how to interact with others (especially peers), problem-solve, and build trust in others.

Both studies appear to prove the importance of environment in long-term health, as well as lay the groundwork for further study on siblings and mental health.

This vital relationship may be key to reducing risk factors in children before they manifest later in life and provides fascinating insight into the complexity and importance of the nuclear family unit.