We need the original JSON pasted with your answer and the stack trace. Sniffing through your code though,
are you sure your JSON is valid? You can verify with this: http://jsonlint.com
at JSONObject c = genre.getJSONObject(i);, are you sure the genre array contains JSONObjects, and not Strings representing JSON?
at jObj = new JSONObject(json);, are you sure that json represents valid JSON?
are you sure that the value corresponding to TAG_ID is a String type, and not a long say? String id = c.getString(TAG_ID); could perhaps be: long id = c.getLong(TAG_ID);
It is hard to be of more help without further assistance from you.
Edit: Based on your comment, where you post your JSON format, you will need to answer point (3) above. Your id field has an integer type, not String type.