Maybe it’s your mother. Maybe it’s your uncle or sister. Watching a family member suffer from depression can be difficult, leading to feelings of helplessness.

In addition to that helplessness, you may also feel concern about genetic links to depression, leading to the all-consuming question, “Is depression hereditary?”

The Depression Gene

Last year, a British team isolated a gene that appears to be prevalent in multiple family members suffering from depression. The chromosome, 3p25-26, was found in more than 800 families with recurrent depression in the study. Scientists have said as many as 40 percent of those suffering from depression can be traced back to a genetic link, with environmental and other factors comprising the remaining 60 percent.

Research has shown that those whose parents or siblings suffered from depression are up to three times more likely to suffer from depression as those with no close relative suffering from the disease. While this can certainly be traced to heredity, it can also be argued that environment is to blame.

Environmental vs. Heredity

If an individual grows up in a household with someone suffering from depression, some researchers believe this increases the person’s susceptibility to the disease. Through watching a depressed parent or sibling, for instance, a child may learn to mimic that family member when certain situations occur. While having a parent that spends days in bed may seem unusual to someone whose parent never did such a thing, a child who saw that regularly may assume that as a norm.

In this instance, much of what has been learned about heredity and depression has come from studying twins. In studies, a twin was found 76 percent likely to develop depression if his or her twin suffered from it. When the twins grew up in completely separate environments, that likelihood only decreased to 67 percent. While some instances may be chalked up to family environment, the genetic link is undeniable in studies such as these.

The Serotonin Link

Researchers have linked serotonin to depression. Serotonin is a neurotransmitter, involved in the transmission of nerve impulses. Serotonin is believed to help maintain a "happy feeling," and help keep our moods under control. Scientists believe an imbalance in serotonin can lead to mood issues like depression and even such issues as obsessive-compulsive disorder and panic attacks.

While theories abound as to the reason for the serotonin-depression link, researchers also continue to study serotonin as the key to the genetic link. Problems with the serotonin transporter gene have also been theorized as a cause for depression and researchers have traced prevalence of long and short transporter genes as a possible genetic link.

Types of Depression

A clinical depression is one that recurs numerous times over a person’s lifetime. This is the most common form of depression and affects an estimated three to five percent of the population, it is also more likely to be shared by siblings and offspring. In fact, estimates state that a person with a relative suffering from recurring depression is four or five times more likely to develop depression than the average person.

It is emphasized by many researchers that it is not a singular gene that predisposes someone to develop mental illness as much as a combination of genes that lead to an increased likelihood. Bipolar disorder and anxiety disorders also fall under this predisposition.

The question then remains, should someone whose parent or sibling suffers from depression be worried? And the answer to that is not necessarily. While someone whose parents or siblings were among the ten percent who suffer from situational depression at one point or another may be more likely to also suffer from it, situational depression is only temporary. It is usually brought on by major life events and treatment is available for it. It is certainly something to watch out for, but not something to worry about.