Cortisol is a hormone produced by the adrenal glands in times of stress, and it also plays many roles in your normal bodily functions. It is a multi-purpose hormone that needs to be in the right amount (not too high, not too low) and at the right time. Your genes play a big role in how likely you are to have problems with cortisol.
The hypoxia-inducible factor-1 alpha (HIF1A) gene codes for a transcription factor, that responds to the amount of oxygen available to the cell. This is important in cancer prevention, and several HIF1A genetic variants alter the susceptibility to several types of cancer.
Exposure to childhood trauma, such as exposure to abuse, violence, or repeated stress, can have a long-lasting effect. Genetic differences in the CRHR1 gene are linked to elevated cortisol levels in adults who were exposed to trauma in childhood.