In an age of instant information, it’s not surprising people want to know as much as possible about their risk of developing certain diseases.

Now, mail-order kits allow us a peek at our genetic destinies, though some have questioned the accuracy of such information. A handful of companies have cropped up that both sell the kits and offer genetic counseling based on the results.

Tests using blood samples usually require a prescription, but others ask consumers to simply spit in a tube or swab the inside of their cheek. Prices range from several hundred dollars on up.

The results tell of genetic markers that, if present, may signal susceptibilities to certain health conditions. These markers, called SNPs (or single nucleotide polymorphisms), are variations in gene sequences. SNPs don’t cause disease, but can help determine the chances of developing a certain illness, according to the U.S. Department of Energy’s Genome Program.

Results indicating you’re at above-average risk for contracting a disease don’t guarantee you’ll get it, just as results showing no risk markers don’t mean you won’t. But for some, acting on the information like deciding to quit smoking or make diet changes may help prevent the disease’s development or lessen its effects, according to Navigenics, a genetics testing company.

But test results may not be completely trustworthy. According to a July report by the Government Accountability Office (GAO), the mail-order spit tests are often inaccurate or misleading. Some results directly contradicted others, the GAO told members of a House of Representatives subcommittee.

And even when mutations are found, scientists are not always able to translate these to say exactly how much the odds are of developing a disease are raised.

MyHealthNewsDaily has rounded up some of the genes that genetic tests look for, and exactly what’s known about these genes.