Melissa and Bill Scully
There is some debate over whether Melissa or Bill is older. Melissa was born in 1962 and Scully in 1964, which would be a tight squeeze for Bill. But, Melissa is almost definitly older. In Beyond the Sea, Mrs. Scully says that after returning home from the Cuban Blockade, Captain Scully proposed to her. The Cuban Blockade ended in November 1962, which means that Melissa and Bill are twins (which has never been suggested) or she was born first (and that Mrs. Scully would have been pregnant before her marriage, but that's another story. . .).
Melissa Scully
Bill Scully
X-Connections
Characters
Queenie's X-Files