Suicides seem to run in families, which has led some researchers to look for a potential genetic link. For example, researchers have found that serotonin, a chemical neurotransmitter in the brain, may play a part in suicides. People who commit suicide are thought to have dampened serotonin signaling, and some research has found higher rates of abnormalities in serotonin signaling genes among those who kill themselves. (Sanders, 2012) But it's difficult to tell whether this increase in suicide risk among certain families or lineages is truly genetic or the result of environmental and/or behavioral factors that are passed down through the generations.
If a genetic link exists, it is complicated. There is no single "suicide gene" or simple genetic explanation for such behavior. Anytime you hear a gene reported as a "suicide gene" or an "autism" gene or any other gene, you are being given grossly simplified information. Even when researchers do find an association between a particular gene and a disorder, it typically only explains 5% or 10% of the variance at most, and even in these instances, it's important to remember that correlation does not equal causation.
That said, we do know that for whatever reason, suicide risk is elevated in families with a history of addiction, depression, or prior suicides; factors which often coincide to one another. Suicide is also more prevalent among whites than African Americans. Family environment and parenting can also play a role. For example, having highly critical parents can often predispose one towards suicide, because this creates high levels of self blame and self-criticism that are the fuel behind self-destructive actions.
Developmental issues in the earliest stages of life can also increase a person's risk of suicide. For example, it's been found that baby boys born prematurely are 4-times more likely to attempt suicide later in life than those born at full term, possibly due to reduced serotonin activity in the brain. (Wenner, 2009B)
Protective factors against suicide
On the opposite end, several factors have been identified as things that reduce the risk of a person committing suicide:
1. An intact marriage or other social supports
2. Active faith or religious affiliation
3. The presence of young dependant children at home
4. Supportive relationship with a caregiver
5. The absence of substance abuse or depression
6. Living in an area with close access to medical and mental health resources
7. The awareness that suicide is the product of mental illness
8. Proven problem solving and effective coping skills