My ancestors were turkish and this has always confused me. Why are turks associated with crime/mafia/gangs? In The Godfather, The Usual Suspects, etc... even in the movie Snatch. Why?

Welcome, Turk! Hope to see many more thoughtful posts from you!
In general, there's never a shortage of prejudice, unfortunately, against people who don't speak, look like, worship, etc., like the majority. But in the case of GF, Virgil Sollozzo, a Sicilian, was called "The Turk" because he had poppy fields in Turkey that produced the opium base for his heroin trade, and because he had a Turkish wife.

Sorry, Turkish but there's a lot of connections between drugs, particularly heroin, and Turkey. It's pretty much the go between to a lot of points from the middle east to western Europe, the UK and sometimes America.

Where i live in North London, there is a large Turkish/Kurdish community with many organized gangs.

Check this link out.
http://news.bbc.co.uk/1/hi/uk/2284780.stm