Actors Ben Affleck (L) and Matt Damon, partners in Live Planet Productions, arrive for a party celebrating Project Greenlight February 26, 2001 in Hollywood. Project Greenlight, a screenwriting forum, has selected three finalists out of 10,000 screenplays submitted in a contest which will pick one winner who will have their screenplay produced in a $1 million budget film by Miramax Films. Affleck, Damon and their partner will executive produce the film slated for release in 2002. (Photo: Reuters)

Actors Ben Affleck and Matt Damon who are very close friends, are also cousins, the Boston Herald reported on Friday.

Affleck and Damon are 10th cousins, according to the New England Historic Genealogical Society, the oldest genealogy research center in the U.S.

The actors share in common a 10th-grade grandfather named William Knowlton of Ipswich, a bricklayer who died in 1655, the paper noted.

The actors are related on their father's side.