DNA transfer during social interactions

Multiple DNA transfer has increasingly been brought up in court as potential means for the presence of the defendants DNA at the crime scene or on a piece of evidence. This has prompted several investigations into DNA transfer under very controlled and semi-controlled conditions, however little is published about DNA transfer in "uncontrolled" or real life situations. Here we examined the effects of multiple direct and indirect transfer of DNA within a small group of people and objects: three individuals participating in a social interaction of having a drink (jug of juice) together for 20. min. At the end of the tests all the surfaces of interest were sampled and analyzed. In many instances the last person or the only person to come in contact with the object was the main or the only depositor of the DNA detected on it. The jug was a clear vector for secondary DNA transfer. Interestingly, in many instances the participants acted as vectors for foreign DNA transfer.