Three actors who would be good in some project together playing brothers or blood relations: Jeremy Renner, Nathan Fillion and Martin Freeman.
Maybe I'm weird though. I don't think they look exactly alike, I just think they have similar types of facial structure that would lend itself to playing family. Side-by-side for comparison.
Tricky for them to play brothers though, because they were all born the same year, 1971. (Is fraternal triplets a thing that can happen? Or Nathan could play a cousin and Martin and Jeremy could play fraternal twins because they are more similar to each other than to Nathan.)
Also born in 1971, Richard Armitage and David Tennant. '71 was a very good year for actors. Also, David Tennant appears to have done a sequel to "Nativity!" which starred Martin Freeman. So I'm going to need to track that down at some point.
In other news, I'm very distractible, and am going to go to sleep before I do anything sillier than posting this.