Muslims and Sicilians woven from same cloth?

If you have ever wondered how the Sicilian Mafia, known as having the worst kind of murdering bastards in the Mafia hierarchy, could kill so heartlessly and yet  profess to be peaceful Catholics, attend Sunday services and  contribute to the Church's coffers ... wonder no more.  Their DNA can be traced back to murderous Muslims.

Richard Tada writing at WeeklyStandard:
...A band of Muslim raiders  sacked Rome in 846 a.d., plundering the city’s churches and getting clean away with their loot. They had come from Palermo, in Sicily, which had been in Muslim hands for 15 years. Sicily was then on its way to becoming a predominantly Islamic and Arabic-speaking island, and it remained under Muslim rule for over two centuries, until the Normans conquered it in the late 11th century.  

Expressions of astonishment that the land of cannoli and the Mafia was once part of the Islamic world may be forgiven, since this is the first detailed book on the period to be written in English. Leonard Chiarelli directs the Aziz S. Atiya Library for Middle East Studies at the University of Utah; among his scholarly achievements is detecting the presence of the heterodox Ibadite sect in Muslim Sicily. His book is comprehensive and reliable—if at times dry and lacking in eye-catching detail. This is due, in part, to his sources: There were Arab historians who focused on Sicily, but their works have not survived; thus it becomes necessary to cobble together references to Sicily from later Muslim historians whose primary interest was North Africa. The sole contemporary source is the Cambridge Chronicle (so-called because the first copy to be studied in modern times was held by Cambridge University), which tersely recounts events from 812 to 964.............

....The Fatimid caliph was determined to reduce Christians to second-class dhimmi status—subordinating them and requiring them to pay an annual poll tax. Thus, in 962, a Muslim army marched on the Christian town of Taormina, on Sicily’s northeastern coast. The residents resisted for several months before surrendering. They were then sold into slavery, and the town was resettled by Sicilian Muslims; Taormina itself was renamed al-Mu’izziyah in honor of the reigning Fatimid caliph. The Fatimids then defeated a relief force sent from Byzantine Calabria, and they took the last autonomous Christian community—the inland town of Rametta—in 965. Rametta was also repopulated by Sicilian Muslims as part of a deliberate Fatimid policy of accelerating Islamization by introducing Muslim residents into Christian areas.....