( - We're all just one impulsive Google images search away from facing the unblinking darkness that lurks within the heart of man. But that black pit of twisted evil and decay shouldn't surprise anybody; it's rooted in our genetic makeup. Literally.

#6 - Ancient Diseases
Back in biology class, you were probably taught that DNA was a sensible, organized system. When they called it "the building blocks of life," you probably pictured DNA as a series of neatly edged Legos snapping together to form a cohesive whole. When in reality, DNA is more like an old scrapbook that someone has torn up, pasted back together, filled with old newspaper clippings about murder and then taken into the bathroom with them.

In the distant past, retroviruses picked up by our ancestors would occasionally find their way into the sex organs, and the newly virused-up DNA was passed along to their children. As a result of all this virus-laden boning, we modern humans have about 100,000 of these microscopic gate-crashers cluttering up our DNA. When you add in the assorted genetic trash they've left behind, more than 40 percent of human DNA is made up of ancient, sinister and almost certainly cursed viruses.

#5 - Reanimated Zombie DNA
It's not just Madness Viruses cluttering up humanity's building blocks. The useful parts of DNA, which give us things like hair color and lungs, make up only around 2 percent of the human genome. Aside from the viruses, the other 98 percent is made up of allegedly "dead" genetic material: unused DNA sequences that might have once been useful but that now have no known purpose, like the human appendix, or Utah. 

Under certain circumstances, long-dead DNA sequences can suddenly return to life, giving their human carriers an all-you-can-catch buffet of horrible diseases. A common form of muscular dystrophy, FSHD, is caused by a "dead" gene present in all humans. But it's only "dead" because it's missing one specific sequence that allows it to be successfully transcribed. All it takes is one mutation, and the gene rises from the grave to wreak its terrible revenge on humanity.

#4 - Nonhuman DNA
Squeezed into your cells among the Zombie Genes and Madness Viruses, you'll also find DNA that never belonged to a human being. We know what you're assuming, but you can take that spider out of the microwave; it's not superpowered animal DNA. It's Neanderthal.

A group of scientists have been reconstructing the Neanderthal genome from fossilized bones recently, and when they compared their results with genomes of various humans from around the world, they discovered that most modern humans in Europe and Asia share between 1 and 4 percent of their genome with Neanderthals -- a trait that is not found among people from sub-Saharan Africa. In other words, if you're reading this and you have any European or Asian ancestors at all, you're technically not fully human and therefore must be destroyed before you can infect others.

#3 - Grandparent-Based Death Time Bombs
We've mentioned before that your father's smoking could have made you fat. What we didn't mention, though, was that your grandparents' actions could also have doomed you to a short and unhappy life. Man, what did you do to piss off all of history? 'Cause it sure seems to hate the crap out of you.

A study in Sweden revealed a strange pattern in a rural community that had gone through periods of both famine and abundance in the 19th century. The study found that the grandsons of men who'd had childhoods coinciding with abundant years -- i.e., the ones who had stuffed their faces with grain for a season or two -- had a life expectancy of 32 years less than the grandsons of those who had experienced famine, with the deaths caused mainly by diabetes, heart disease and presumably the shame of having extremely fat grandparents.

#2.Bug Poop
The assassin bug of South America lands on the faces of sleeping humans and sucks their blood while pooping on them at the same time, proving once again that nature is a sick and murderous pervert. Wait, did you just have a seizure? Weren't you reading an article on DNA? What the hell are we doing talking about bugs? Oh, God, there aren't bugs in your DNA, are there?! Relax, relax, it's nothing like that: It's just a parasite that lives in the poop floating in your bloodstream. See, when the bug's victim scratches the bite, the crap sitting on the wound enters his system. And since assassin bugs carry the parasite T. cruzi, you get a free bonus prize... 

Researchers who deliberately infected chicken eggs with T. cruzi and then tested the offspring of the infected chickens that emerged found that not only did those chickens have the parasite DNA, but so did their offspring, and so on. But keep in mind that T. cruzi isn't necessarily the only parasite in our DNA, just the first we've discovered.

#1.The Twin That You Murdered as a Fetus
Regular Cracked readers probably know by now that babies are capable of murder in the womb, because that's our end goal: teaching you things that you can never un-know. But even womb murder isn't the end of the story. In some cases, you can end up absorbing your newly dead twin and having its DNA live on inside you, a condition known formally as "chimerism" and informally as "what happens when God stays up late watching movies by David Lynch."

Chimerism is thought to be rare but also massively underdiagnosed, since it's undetectable outside of DNA testing, which doesn't happen to normal folks all that often. Potential symptoms can include slightly different-colored eyes, uneven skin pigmentation and waking up at night to find 'YOU KILLED ME' written on the bathroom mirror just before being strangled by your own reflection.