You are obviously in a no win situation and are, more likely than not, seen as a threat. Being seen as a threat occurs in an environment where you are producing and others are underproducing. Because of that the under producers want you gone. And, they apparently have the upper hand - due to being relatives or friends of those in power - and will continue to work against you for as long as you are there. Your best bet is to not say a word, but to quietly find a new job with a company that you can see is not steeped in nepotism. If you stay, you may not only lose your job but also damage your reputation.