What About the Gault Children?

Now I know I'm supposed to be researching the Stones, but the Gaults are tied to the Stones through marriage... so I'm in the vicinity of doing what I'm supposed to be doing.

The family history states:

After the [Civil] War, her (Kansas Elizabeth Gault Stone) mother (Great-Grandmother Gault) loaded her few possessions and three children (Cansas Eliz., Aunt Belle and Uncle John Gault) into an ox cart and came to Texas and settled near Honey Grove in Grayson County and that is where your Grandfather William Thomas [Stone] was born in September of 1884.

Okay, so the census records show that Martha/Milinda Gault had the following children: John, Mary Jane, Kansas E., Belle, William and Ellen T. All of them were born in Tennessee. And all of them were living in Fannin County, Texas as of the 1870 census (the first census taken after the Civil War). So why does the family history only mention three children: K/Cansas, Belle and John?

PS - Also of note is that Honey Grove is not in Grayson County, but in Fannin County.