"David's family used to be involved with the religious cult Worldwide Church of God," Ms Fisher wrote on her blog less than two weeks ago.
While the church, established in New Zealand in 1967, now describes itself as "simply an Evangelical church with normal orthodox ideology", Pastor Dennis Richards said it used to be known as a "cult".
"We used to get the label 'cult' which was to do with issues over doctrine, things we believed that were outside core orthodox belief," he said.
The Worldwide Church of God, known as Grace Communion International at its headquarters in California, was formed in the early 1930s by Herbert Armstrong, who enthusiastically taught his "unusual doctrines" to his followers.
Mr Richards said that after Armstrong's death in 1986, church leaders began to realise that many of his teachings were not biblical and the church underwent "fundamental changes" to align itself with orthodox beliefs.
"We researched our beliefs thoroughly and we found error in statement of faith."
Mr Richards said the changes caused the church to lose a large proportion of its members, who had since split into their own denominations.
The Queensland Child Protection Investigation Unit, which is handling the case, also said some members of the Fisher family came from New Zealand.
Fisher has been remanded in custody and is due to appear in court next month.