Poison ivy and other poison plant rashes canât be spread from person to person. But it is possible to pick up the rash from plant oil that may have stuck to clothing, pets, garden tools, and other items that have come in contact with these plants.
Biological Causes. Some individuals are more vulnerable to depression than others due to their own unique biological factors, such as presence of depression-triggering genes. This means that depression is hereditary; hence it tends to run in families, notes the Black Dog Institute.nother biological trigger of depression is abnormal brain structure and chemistry. The report released by the National Institute for Mental health notes that the brain structure of an individual with depression is slightly different from the rest of individuals who do not have the disorder.
That is the case for major depression. Heritability is probably 40-50%, and might be higher for severe depression. This could mean that in most cases of depression, around 50% of the cause is genetic, and around 50% is unrelated to genes (psychological or physical factors).Or it could mean that in some cases, the tendency to become depressed is almost completely genetic, and in other cases it is not really genetic at all.eritability is probably 40-50%, and might be higher for severe depression. This could mean that in most cases of depression, around 50% of the cause is genetic, and around 50% is unrelated to genes (psychological or physical factors).