1841, Andreas, district 3, page 4, West Craig
William Cain, 40, weaver
Frances, 40
Ellen, 10
Esther, 8
Jane, 6
Robert, 5
Edward, 2 months
William, 15, apprentice shoemaker
Thomas, 15, apprentice weaver
John, 13
James 11

William & Thomas were not twins - it is the way ages were recorded in 1841.

Have a look at the IGI at www.familysearch.org where you will find the the bapismal dates for the above,