In most cases, a simple mouth swab collecting skin cells that naturally flake off is all that is necessary for a DNA collection. The swabs need to be sterile medical grade swabs. This type of sample can be used for legal DNA paternity tests and at home testing kits.
If one of the individuals testing has had a bone marrow transplant, they will require a different sample collection. Most of the time, the sample taken in this situation would be a blood sample.
If an individual testing has had a blood transfusion, they would not be able to use a blood sample.
DNA samples may have to come directly from a coroner’s office or funeral home. In this situation, there are multiple options for samples. The lab can accept, blood, tissue, hair with the root attached, or finger nail clippings with skin. The options are not limited to the list above and you may need to check with your lab for additional options. Non-standard samples may only be accepted if one of the individuals is deceased.