Young kids who lose a parent to suicide (about 10,000 a year in the US) are 3 times more likely to commit suicide themselves than kids who lost a parent due to illness or accident, and they are also at risk for a bunch of other mental problems. By 12, the rate drops to twice normal, and 18, the issue vanishes. Kids who lost a parent due to illness are more likely to be hospitalized but not more likely to commit suicide.
I guess this isn't a surprise. The act of suicide is pretty good evidence of some sort of mental problem going on, such as depression, and lots of mental problems, including depression, have a genetic component. What's odd is that it doesn't affect adults. I guess the stress is greater on a younger person, and some sort of hormonal or epigenetic influence happens in the brain.