Jesus was 12 yrs old went he first went to temple.   The age of accountability according to the bible is on or around 12 yrs old.... Depending when the child hits maturity/puberty.  Not every child hits this at age 12, but the bible gives us the general age of accountability, which again is 12 yrs old, the same age Jesus Christ was when he first went to temple.
From what I read in the bible, every child on the face of the earth whom has not hit maturity/puberty, will be taken in the rapture.  Those whom have already reached maturity/puberty, and have not accepted christ will NOT be included in the rapture.