Now in this case Tina’s friend’s results didn’t give any evidence either way about whether her dad was her biological dad (she’d need his results to confirm that). Still, the results were confusing enough that she needed reassurance from Tina.
And just because in this case the test didn’t show her relationship to her father, that doesn’t mean that these tests can’t sometimes reveal a dad who isn’t biologically related to his child. They can and they do. In fact, given that around 2% of men are in this situation, more and more people are going to find out their dad isn’t related to them (or that a sister is actually a half-sister and so on) as more and more people get tested.
In another scenario, Tina is talking to her sister about getting a BRCA test done because their mother got breast cancer at a very early age. People with certain DNA differences in their BRCA gene(s) are at a much higher risk of getting breast cancer in their lifetime. As you’ll see, during the conversation, Tina’s sister comes to realize that if Tina tests positive, then she has 50% of testing positive too (assuming Tina got the mutated BRCA gene from one of her parents). And that brings up some interesting consequences:
If Tina gets a positive result, should she tell her sister? If she does, then her sister will learn that she almost certainly has a 50% chance of having it as well. What if she didn’t want to know?
Of course this is a made up example (although people do deal with this problem all the time). Below is a video of a real life example of two sisters, Lani and Sherry, who decide to have a BRCA test because breast cancer runs in their family:
Now we see the sisters dealing with survivor guilt, anger and who knows what else. Luckily they had a genetic counselor to help them deal with these issues. Not everyone who takes an online test will.
We also deal with a couple of other situations too. In one scenario, Tina is trying to decide whether to get an online test to see if she is a carrier for the genetic disease cystic fibrosis. And in the other Tina is trying to decide whether or not to get a genetic test for Alzheimer’s disease. Neither decision is as easy as you think.
Don’t get the wrong idea, none of these are designed to say online genetic tests are bad and you shouldn’t take them. They can help you make informed choices like Angelina Jolie did recently when she tested positive for a DNA difference in her BRCA1 gene that significantly increased her risks for breast cancer. We wanted to make these videos so people could be introduced to a few of the potential pitfalls of these sorts of tests and so can make a better informed decision.
For example, I thought through these possibilities and none of them stopped me! I took a 23andMe test a few years back and couldn’t be happier. It was so cool to see the instructions for me written in the genetic code.
I can see the glitch that explains my red beard and when combined with a similar glitch from my wife, my son’s red hair. I can see the reason (well, one of them) for my blue eyes and the one for why I can’t taste the bitter chemical PTC and lots more. Heck, I even saw a hint of African on one of my chromosomes (although this was not verified with a second test from Ancestry.com.)
The test also provided a huge amount of information about what my genes can tell me about my future disease risk. This is where someone who worries a lot might get very freaked out. Lots of diseases, lots of potential risk.
Since I have a background in genetics, I know to take most of this health risk data with a huge grain of salt. As a recent study showed, depending on the studies a company decides to include and the algorithm it uses to predict risk, you can end up with very different risks. Sometimes one company will say you are at an increased risk for a disease while another says you are a decreased risk.