Hi! I am just here to remind you that everyone has insecurities. I have many. My voice has always been one and so just recently I started to send video streaks with my cousin over Snapchat. I would always replay the video and finally about 2-3 weeks in I got used to my own voice. I now send videos to her and my friends without replaying the audio. No one has ever commented bad things per say about my voice but I've always hated it. Now, if you mean you hate more of your singing voice I don't sing so I can't say much but in middle school while I was in choir my teacher had always said that the more you practice the better you get. He recommended that we do vocal exercises during our free time. I am sure it worked for the people who actually did them. Never the less though, I am sure your voice is super pretty and who knows you sister may just be jealous! Hope this helps! xx