My friends tell me I'm a good singer but my dad says I suck at it and my brothers say don't ever sing again. What should I do?

I really like singing but whenever I try to sing, my dad says, "I advice you to do something else. Find a new passion. I gotta be honest sweetheart, you're bad at singing." I was shocked. My uncle said, "Oh no don't let Esmie (me) sing! She'll destroy your hearing." I knew he was joking but it hurt my feelings. My brothers tell me straight up that my singing sucks. One said, "Your singing is terrible. I rather hear a dog cry than you sing." My friends said I'm good. Why is my dad and brother discouraging me from singing? I have a cousin who is an AMAZING and they love her singing. Why are people talking about how bad my singing is?