Does DNA on skin prove someone touched you?

No.

DNA detected on skin does not necessarily mean a person directly touched that area.

Skin is constantly exposed to biological material through everyday contact with people, objects, clothing, and shared environments. DNA can be transferred indirectly and may be present without direct physical contact occurring.

DNA may also persist for varying periods and may move after initial deposition. Its presence does not establish when it was deposited or whether it relates to a specific event.

Laboratory testing can detect DNA and sometimes identify a contributor, but it cannot determine the pathway by which the DNA arrived, whether the contact was direct, or when it occurred.