Could at home DNA tests open doors to your history?

HOUSTON, Texas (KTRK) -- Who are you and where did you come from? Those may still be mysteries in your life, and thanks to new popular at home DNA tests, the questions to our past are becoming easier to answer. But do simple DNA tests really work? Are they worth the cost? And what if you find out something you didn't want to know?

That desire to know the past and maybe the future, has fueled the popularity of at home DNA test kits. They promise to detail your lineage and your genetic markers for nearly a hundred diseases from Alzheimer's to Parkinson's.

With companies like 23andMe and ancestry.com, you sign up online and pay a fee which ranges from $60 to $200. They'll send you a kit where you simply spit in a test tube or swab your cheek and send it back. They'll analyze it for hundreds of thousands of genetic markers, which could be the keys to your ethnicity.

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Adopted at birth, Eric Spillane spent almost 40 years wondering about his family tree.

"70 percent British, 30 percent Irish for me" Eric Spillane shared with us.

That was his DNA result from 23andMe.

"It helps an adoptive person be able to put some tangible pieces around who am I and where did I come from" Spillane said.

UH law professor Jessica Roberts said, "It can be a shock to the system if you really think you're a member of an ethnic group and your test show otherwise."

Roberts says that happens quite often. Someone may think they're Italian based on their name, but DNA tests might show something different. They keep your information and often market it raising privacy concerns. But Roberts says you can opt out of sharing it.

"With the DNA ancestry test, there's not much to be afraid of except perhaps getting an unexpected result" Roberts said.

Former astronaut Scott Kelly and twin brother Mark both took the test.

"I think being part of the database means you never know when you learn something new about a relative or family connection," Scott told us.

Kelly discovered he has dozens of distant cousins, people you can contact through company databases if you choose.

"It actually made me feel more connected to my dad," Roberts said.

She took the test too because her father was adopted, and she's having her first baby.

"And now we know more about her background and ancestry it gives us the opportunity to share that with her that's something special, without these tests we wouldn't have had that chance," Roberts said.

"I think it's fascinating. I teach science and so to have opportunity to this is really neat," Alec Fuentes told us.

After his test, Fuentes says the world seems a lot smaller and a lot more connected.

"And it kind of brings it all together like we are all one," Fuentes said.

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