Earlier today there was great furor over a claim by a United Nations official that the Islamic State had ordered that women in Mosul aged 11 to 46 must undergo female genital mutilation (FGM, "female circumcision"). The original allegation appears to have been without foundation; even ISIS has denied it. It soon became clear that reports coming out of the Islamic State made no mention of it, and something seemed wrong with the story from the beginning. FGM is extremely widespread in North Africa and Sub-Saharan Africa, where it is by no means limited to Muslim groups (and is often enforced by the females of the family); outside of Egypt and Nigeria it it is not usually part of an Islamist/jihadist agenda, and it is not a traditional practice in most of the fertile crescent.
While one lesson of this story is to check your facts, especially if you are a UN official, another lesson is that almost anything said about ISIS will be believable. While ISIS denied this story, it has not denied crucifixions, mass executions, destruction of holy sites, killing and expulsion of Shi‘ites, threats of forced conversion against Christians, ethnic cleansing of Yazidis, Shabak, and Kurds, and so on. So while they may be innocent of the FGM charge, they're guilty of more than enough.