Researchers say that if you are having a bad hair day, it might not be your fault.
Genes appear to control hair patterns
They have identified a gene - called frizzled 6 - which controls hair patterns.
It may explain why some people have kiss-curls and some bushy eyebrows.
The research, led by Johns Hopkins University in Maryland, is published in the journal Proceedings of the National Academy of Sciences.
Although the gene was discovered in mice, the researchers believe it could well do the same job in humans.
To study exactly how it worked, the scientists bred genetically modified mice that lacked the gene.
They found that although the animals were normal and healthy, they had unusual whirling patterns in the hair on their head, chest and hind feet.
Some also had tufts and ridges in the hair on their head.
The researchers examined the seemingly unruly hair follicles under a microscope, and found that they had a normal appearance.
They believe that the direction of hair growth seems to be controlled by skin cells around the base of the hair - rather than the hair root itself.
The researchers believe their discovery could have medical applications as there is a whole family of Frizzled genes.
One affects the development of blood vessels in the eye, and another determines the direction of growth of nerves in the spinal cord.
Researcher Dr Jeremy Nathans said the genes probably played a significant role in controlling patterns of development in the embryo.
Frizzled genes were first discovered in fruit flies, where they control wing hair and bristle patterns.
A recent study has suggested that the orientation of hair whorls on the scalp may be linked to left or right handedness.