The house is haunted, but not in the way you might think. In a number of quiet family cemeteries in Oklahoma, grave houses or spirit houses, as they are known, dot the landscape: little, physical manifestations of tradition, heritage, family, and grief. Some of these miniature houses are new, made of fresh two-by-fours and with simple thatched roofs, others are so old that they appear rough hewn, from decay and exposure. Some are large and imposing, with two stories and intricate doorways. Some are so small that there is no…