If you own a pair of hair extensions or are planning to, you’re probably wondering where they come from and do they possibly contain someone else’s DNA? With this burning question in mind, I decided to uncover the truth—here’s what science had to say.
So do hair extensions contain DNA? Since human hair extensions are made from hair that has been cut off rather than plucked from the root follicle, they DO NOT have DNA. This is because the live DNA is located in the hair follicle at the base of the hair. Hair that is cut off will not contain the DNA of the original owner.
But keep reading. There is a caveat to this. Cut off hair might still contain Mitochondrial DNA—which tells you where your ancestors come from. But before we get into this, let’s look into a common question. The answer might surprise you!
“If Someone Wearing my Donated Hair Commits a Crime, Can I be Held Accountable?”
While it is absolutely possible to get DNA from human hair, it is only useful if you have the actual hair follicle. A simple shaft of the hair, no matter how long, will not contain sufficient amounts of genetic information to convict someone of a crime.
So no, it would be virtually impossible to identify a hair extension donor as a criminal, or vice versa, just from using hair from the extensions. Let’s explore deeper as to why this is so:
- A conviction would require nuclear testing. Both Y-DNA and autosomal testing can be used to gauge genetic information about the individual when tested by forensics. Both of these methods involve nuclear testing, meaning they require information from the nucleus of the cell.
- Hair extensions only contain the hair shaft. Since we are looking at hair extensions, meaning we only have the hair shaft as evidence of DNA, we cannot use this as DNA evidence as the hair shaft simply does not contain nuclear DNA.
- The hair follicle is missing. Since the nucleus of the cell, in this case, would be located within the hair follicle, this would not be possible as the follicle is missing.
- Once the hair has been cut off from the host, the DNA breaks down quickly. As mentioned above, once the hair has been removed, the DNA begins to break down, meaning that there will be less viable DNA to work with.
At a quick glance at the diagram below, you can see that the hair follicle, which contains the nucleus and the DNA, is embedded beneath the skin’s surface. Once the hair has been cut off above the skin, most of the useful DNA has been left behind.
If anything, the person wearing your donated hair would most likely be held accountable as there would be traces of their own DNA in the hair extensions.
For example, traces of their perspiration or skin cells would contain DNA that forensics would pick up on and be able to use as evidence before they even considered looking at your hair for DNA.
Can Mitochondrial DNA—Ancestors DNA—be Found in Hair Extensions?
It turns out that cut shafts of hair are not entirely useless—Mitochondrial DNA can be located along the hair shaft, and can only be used to test very limited factors.
Here’s what the Mitochondrial DNA test can be used to determine:
- Whether two people share the same maternal line. Or simply put if you’re related to someone.
- Species identification. To test if you’re truly human!
Unfortunately, unless you can identify a little white ball on the tip of the hair shaft, the above-mentioned tests are the only ones that can be utilized when dealing with mitochondrial DNA.
Although mitochondrial DNA may not contain the complete human genome, they are by far more abundant than its counterpart, the nucleus. In fact, there are often hundreds of mitochondria located within a cell—however, there is only one nucleus.
This means that although they are not as useful to researchers, they are more commonly used as they are more easily accessible when forensics and researchers have no other choice.
“Because of the known difficulty in getting reliable information from hair morphology and the difficulty in extracting DNA from it, very often hair that comes in as evidence doesn’t get looked at at all.”George Sansabaugh, professor of biomedical and forensic sciences at the University of California
Hair DNA Testing: How Does it Work?
The current problem that forensic scientists face these days is that DNA breaks down pretty quickly when it’s not inside living cells. This means that once the hair has been removed from the person, there’s not much useful DNA left.
The only traces of DNA that can actually survive inside the hair is hidden inside mitochondrial cells. Unfortunately for forensic scientists, these mitochondrial cells do not contain the required information for most useful tests.
Detectives and criminal investigators focus only on nuclear DNA when they are testing human hairs for traces of DNA. Traces of nuclear DNA can only be found in the nucleus of the follicle of the hair. Most investigative companies will not use the hair shaft alone to get any kind of information in their tests.
“The hair follicle at the base of human hairs contains cellular material rich in DNA. In order to be used for DNA analysis, the hair must have been pulled from the body — hairs that have been broken off do not contain DNA.”The Biology Project
How Long Does DNA Survive in Hair Extensions?
Firstly, it is important to note that if the hair has been cut off from the shaft there will only be traces of mitochondrial DNA—there will be no nucleic DNA present.
The shelf life of DNA once it has been removed from the human head depends on a variety of factors, however, here’s the short answer.
If the hair extensions are exposed to the sun and elements, the DNA will only survive for a few weeks. On the other hand, if the hair is buried underground, the DNA could last up to 1,000 to 10,000 years.
Keep in mind that all hair is washed, bleached, dyed or cut before it is processed and sold to customers in order to disinfect. So the chances of there being DNA traces in your weaves or extensions are extremely unlikely.
When the hair is washed, it is exposed to large amounts of chemicals such as alcohol and bleach which are known to not only disinfect but also destroy traces of DNA.
The very tiny amount of mitochondrial DNA would be so small on the donor’s shaft of hair that it would be practically non-existent by the time the next wearer receives the extensions.
To conclude, the chances of your hair extensions containing the DNA of its previous owner are extremely unlikely due to the fact that that DNA breaks down quickly once it has been removed from the living host. Any DNA that would possibly still remain after the hair is removed would most likely be completely wiped during the intense washing, bleaching, and dyeing that the hair is exposed to when produced.
How old was the oldest DNA ever found? Surprisingly, the oldest DNA sample was found in Greenland and was estimated to be between 450,000 to 800,000 years old. The DNA was located in frozen mud and contained DNA from butterflies, pine trees and other organisms. As far as humans are concerned, the oldest genetic material found was estimated to be between 5000 and 7000 years old.
Could my hair extensions come from animals or corpses? Unfortunately, there is no current regulation in the hair trade industry, meaning that it will be rather difficult to trace the exact origins of your hair. As mentioned above, if you are purchasing high-quality hair extensions from a reputable company, there is certainly a much lower chance that your extensions are coming from any animals or corpses.