Why do people think Im always being mean?

Like even though I dont think I am people are always saying that Im saying stuff horridly, like today I went to my sister 'if you want some chips then you can ring mom up' and then she said that I was being horrible! and just my dad had just came back from a funeral and all I said was 'how old was his children? (the man who died) and my dad started having a massive go at me! I try to be as friendly as I can possibly be but people still think that I am being nasty or disrespectful and I can honestly say Im not! It happens all the time :(