question: Were M3 , M4 , M5 , and M6 directed by a person whose sibling played M1 and M2
query: SELECT count(*) WHERE {
  ?x0 a ns:people.person .
  ?x0 ns:people.person.sibling_s/ns:people.sibling_relationship.sibling|ns:fictional_universe.fictional_character.siblings/ns:fictional_universe.sibling_relationship_of_fictional_characters.siblings ?x1 .
  ?x1 ns:film.actor.film/ns:film.performance.character M1 .
  ?x1 ns:film.actor.film/ns:film.performance.character M2 .
  FILTER ( ?x0 != ?x1 ) .
  M3 ns:film.film.directed_by ?x0 .
  M4 ns:film.film.directed_by ?x0 .
  M5 ns:film.film.directed_by ?x0 .
  M6 ns:film.film.directed_by ?x0
  }