The Children's Commissioner has said the public will be shocked at both the scale of family child sex abuse and the way in which victims are treated.
Dame Maggie Atkinson has ordered a two-year national review of chid sex abuse within family environments, including arising from forced marriages.
"Society is rightly horrified by child sexual abuse," Dame Maggie said.
"Most of our children are raised in secure, loving homes but I am sure very many of us will be disturbed by how much abuse within the family environment goes unreported and how little is done to support the children who suffer," she added.
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The victims were collecting permits and escorts a day after their home town was liberated from the extremists.
Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.