Am I "Sicilian" (Important question)?

As Y-DNA on traces the direct male lineage, you would need to look for males in your line who are of Sicilian heritage but yes if you are in that haplogroup you would have some Sicilian ancestry. As for you cousin, he had a different father so it's reasonable that his haplogroup doesn't match yours. If you have further questions about your test results, you should contact you test provider most answer questions by email. If your doesn't go to a href="http://www.familytreedna.com" rel="nofollow"http://www.familytreedna.com/a and read their material to see if they can clear up some of your questions.