Every adult male with the surname of Hollenkamp is invited to participate no matter where in the world you reside. Females are also welcome but it is best to have a male relative with that surname be a female's YDNA-proxy, e.g. her brother; her father; her uncle; her male cousins. This group also invites adult males who can trace their strictly male line ancestors to a Hollenkamp forefather. The project aims to make it’s genetic and genealogical findings available under the associated Hollenkamp One Name Study project.