How They'll Know if Justin Bieber Is a Baby Daddy

I suspected Justin Bieber was no innocent when I saw him for the first time on television.

It was TMZ, and he must have been 15 at the time. He was being tailed by cameramen who were asking really smart questions like: "What's the best thing about being Justin Bieber?" The tween heartthrob replied: "The girls," like super soberly. It gave me shivers.

So when 20-year-old Mariah Yeater said The Bieb was her baby daddy, my ears perked up. She's got Justin and his lawyer's attention, too. He has agreed to undergo DNA testing, which will out the deceiver in this story: People might lie, but DNA doesn't.

Unless someone mixes up the test tubes, a DNA test is pretty much guaranteed to tell you exactly who fathered a child, granted you've obtained a bit of saliva or blood from everyone involved. DNA paternity testing became available in 1988. Before that fatherhood was more suggested than proven using blood types (paternity could be excluded but not proven). It got a little more accurate in the '70s and '80s with electrophoresis, which could identify certain genetic markers, but not down to the letter like DNA testing can today.

If the paternity suit is bogus, here's why Mariah Yeater is not, perhaps, the sharpest tool in the shed (besides that fact that she will have instigated her own statutory rape investigation). And if it is true, this is why The Biebs is F'd in more ways than one.

1. Pay for it
Mail order home tests cost as little as $79, others can cost between $400 and $2000, depending on how complicated the test is (Are you testing one or more kids? Are you also testing for maternity? How fast do you need it?). There's some controversy over whether the home tests are as good as the in-person ones. We suggest you make certain the test is submissible in court if that's what you need.

2. Get it
Paternity tests these days typically use a simple swab from inside the cheek of the potential family members: daddy, mommy, baby. Spit contains plenty of DNA, since a full complement of your genetic info is present in every cell in your body. Or they might sometimes use blood. You can go to a lab or mail-order your test—more on that below. If you're in more of a hurry, you can test for paternity after the first trimester of pregnancy with amniocentesis or a technique called chorionic villus sampling.

3. Got it
Each parent contributes half the DNA—23 chromosomes each—to their offspring's genetic make up. DNA is made of the nucleic acids adenine, thymine, cytosine and guanine represented by the letters A, T, C and G. They travel in pairs (A binds with T and C binds with G), and together they create that double helix swirl you see in the media pretty much any time DNA is discussed.

4. Read it
Scientists read the story these letter tell using technology such as a polymerase chain reaction, or PCR, which amplifies the DNA into an amount they can more easily examine. Then they look at the father's contribution to the babys genetics, but they don't study his entire genome. That would take too long and be way expensive. Instead, scientists choose DNA markers, usually around 16 of them, then compare those markers to the baby's DNA.

5. Keep track of it
To prevent test-tube mix-ups, technicians split the DNA sample in two and check each one against the other throughout the analysis process.

6. Confirm it
DNA paternity tests are very accurate (about 99.9 percent). They're so accurate that they can even determine paternity by testing DNA from grandparents and cousins, and even using saliva left on a drinking glass.

Not all tests are created equal, at least in the eyes of the law. Some are court-approved while others, often the at-home, mail-in kind, are mostly used for peace of mind—or when deciding to move forward with a lawsuit. We're guessing Biebs et. al. will be springing for the former.

[Nature, DNA Diagnostics Center; Images: Shutterstock/Alila Sao Mai, Associated Press]


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