There could as well be another Winchester in the clan of "Supernatural" according to E! Online's Kristin Dos Santos. Apart from Sam and Dean, their father, John, may have another offspring out there somewhere. The third brother will join the show but no actor has been hired to fill in the role yet.
John, played by Jeffrey Dean Morgan, appears mostly in the first season and was killed off in the second season. His wife Mary, the mother of Sam and Dean appears occasionally in first, second and fourth season. There had been no indication of another son born to the couple in the past episodes yet.
Also on the spoiler chat section, Kristin shares that the evil Alastair has not gone from the show for good. The character played by Mark Rolston will be back later this season, but "in a new, nastier meat sock form".
"Supernatural" will continue the fourth season on January 15 with "Family Remains".