Spit-in-a-tube DNA kits are everywhere nowadays, with dozens of biotech companies offering the opportunity to root around in your genetic code and provide insights into your ancestry, your heritage, your health, or even your family’s dirty secrets.

Journalists from NBC 5 in Chicago recently carried out their own experiment to compare a few of the top home DNA kits on the market, using a sample from reporter Phil Rogers, only to discover the results can vary quite a lot.

They even tested the kits on a dog, Bailey. While most of the companies declared the sample unreadable, Orig3n DNA reportedly failed to note that the DNA belonged to a Labrador Retriever, not a human. Instead, they received a seven-page report explaining that Bailey had superb muscle power and cardiac output, ideal for boxing and endurance bike rides.

Even for the non-canine participant of NBC’s experiment, there was some confusion within the results. Ancestry.com told Rogers his ancestors were most likely (36 percent) from Ireland, Scotland, and Wales, followed by Scandinavia (32 percent) and western Europe (26 percent). My Heritage, however, said that the likelihood was highest for north and western Europe (66.2 percent), followed by Great Britain (18 percent), then Ireland (15.8 percent). Both companies, when asked, said that the difference could be explained by their different algorithms and databases.

Home DNA uses a slightly different form of test to show where your genetic markers appear in the world today. This time for Rogers, his results showed Kuwait, Ireland, Austria, and Afghanistan, Peru, and Guyana. Their sister company, Connect My DNA, showed similar results for Ireland, Austria, and Scotland, followed by Peru, Guyana, and Nicaragua.

As mentioned, these two tests look for present-day genetic markers across the world, so you would not necessarily be able to work out the identity of your ancestors like the other tests. Nevertheless, it goes to show how differently these results could be interpreted by unknowing consumers.

The long and short of it is that home DNA kits are fun and can be fascinating, however, be ready to take your results with some critical thinking (especially if you are a dog).

“It’s not very hard science – maybe it will get better,” Dr Wayne Grody, a UCLA geneticist, told NBC Chicago. “I’d be taking them all with a grain of salt!”

“There might be some vague truth, but those are vague assumptions,” he added. “It’s really like the patent medicines of a hundred years ago.”