Can shaking hands leave DNA?

Yes.

Shaking hands can transfer DNA between people.

Skin cells are shed constantly and can be deposited during brief physical contact, including handshakes, touching objects, or handling shared items. Even short interactions can result in the transfer of detectable biological material in some circumstances.

The amount of DNA transferred varies depending on factors such as pressure, duration of contact, moisture, individual shedding rates, and what happens afterwards. In some cases, DNA may persist on the hands for a period of time or be redistributed through further contact.

Importantly, DNA transferred during a handshake can then be transferred again to other items or surfaces that the person subsequently touches. This is known as tertiary transfer — where DNA moves from one person to another, and then onto a third surface or object without the original person ever contacting that item directly.

DNA detected following a handshake therefore does not indicate what type of interaction occurred, when it took place, or where the original source of the DNA first came from.

Understanding how DNA can move through ordinary contact is critical when interpreting findings, particularly where multiple handling events or shared environments are involved.