Here's why:
* All cells in an individual have the same DNA. This is because all cells originate from a single fertilized egg cell. During cell division, the DNA is copied and passed on to the daughter cells.
* DNA contains the genetic blueprint. This blueprint is the same for all cells in the body. While different cells express different genes, the underlying DNA sequence is identical.
* Exceptions: There are a few exceptions to this rule, such as red blood cells, which lack nuclei and therefore lack DNA. However, the DNA found in cheek cells is the same as the DNA in most other cells in the body.
Therefore, if you were to extract DNA from your cheek cells, it would be identical to the DNA found in your skin cells, muscle cells, hair cells, and so on. This is why DNA testing can be done using samples from different parts of the body.
