Had Othello been able to do an infidelity test he might have avoided strangling Desdemona and save her from dying guiltless death. But infidelity DNA testing was not around in Shakespeare’s times. Today, DNA tests can tell you a lot about any suspicious stains you find on an item of clothing or on bed linen. These tests can even tell you the sex of the donor of the sample and perhaps even who the sample belongs to.

Is it a male or a female?

So you have found a stain on a jacket or on the car seat. You might want to first determine whether this stain belongs to a male or female. The amelogenin sex gene is one of the main sex determining genes in our body. It is found on both the X and the Y chromosome but displays a smaller peak on the Y chromosome when analyzed using the standard laboratory procedure for DNA analysis known as PCR- polymerase chain reaction.

Anyway, scientists can easily determine whether the DNA in the stain is male or female or a mix of both. Furthermore, they might even surprise you- we have had cases where the 2 DNA profiles belonged to people of the same sex (suggesting, for example, that the husband had been cheating with another man)

Types of samples used

Typically the samples used are either blood stains, stains of biological fluid, hairs or items of clothing. However, the range of samples people actually send in is much, much longer. It is important to get a full evaluation of the DNA sample you have at hand. In some cases, the sample may not have been collected or stored well or may simply be unsuitable for testing. A qualified person can tell you how to pack you sample and how likely it is that the test will be successful.

Hair samples are worth a short mention because this is one of the samples which is more over estimated. Yes, hairs are often found lying around the house, especially in the bathroom. Our bodies naturally shed hair, they fall off when we brush our heads, when we wash etc. Many cases where people suspect infidelity are based upon the findings a few stray hairs and people wish to confirm either whether the hairs are male or female hairs (although the length of the hair is often enough in this case) or perhaps they wish to compare the DNA in the hair to the DNA in another sample.

Unfortunately, DNA testing with hair is only possible if you can confirm the root of the hair is still attached (sometimes referred to as a hair follicle). The genetic material needed for a standard DNA test is only to be found in the hair root. The other part of the hair does not contain the type of DNA we require for a DNA test (although it does contain a special type of DNA which is called mitochondrial DNA).

If you do find hairs which still have intact roots, these can then be sent for testing. The recommended number of hairs is between 4 and 6 hairs and the chances of DNA extraction are not too high but neither too low (around 60%).

Do you suspect who your other half is cheating with?

If you have a suspicion of who your other half might be cheating with, you can send a comparison sample for testing. Let’s explain a bit further:

  • The laboratory has already found a male and female DNA profile in the stain you sent in
  • You have a suspicion of who the female profile might belong to
  • By sending in a DNA sample of that person, laboratories can compare the two female profiles and determine whether they belong to the same female or not
  • You can also sensibly ensure that you are not the donor of that DNA profile by sending a sample of your own DNA to exclude you as the donor.

It is important to realize that whilst companies offer DNA infidelity tests, you are free to draw your conclusions from the results of the test. The results will not state that there has been infidelity as this is beyond the scope of science.


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