Any Wilson may join, including those with variant spellings of the surname. The goal of the project is to sort out the different lineages found among those with this surname.
Initial results have revealed a complex set of lineages. The surname Wilson is about 700 years old and appears to have been independently adopted numerous times by individuals or family groups who otherwise have no close patrilineal relationship.
It cannot be the case that there was a single Wilson centuries ago from whom all modern Wilsons descend. There are probably dozens of different lines represented among those who carry the surname, and many more tests will be needed before we can reliably pick out most of the different clusters of related lines. It is already possible to distinguish some English Wilsons from those whose roots lie in Scotland or Ireland. Haplogroup distinctions may point to pre-surname ancestry for different Wilson lines among Vikings, Angles, Saxons, Celts -- even individuals with Middle Eastern roots who may have come to the British Isles during the Roman period.