Failed entire life :(

My auntie used to constantly compare me to my cousin because we both applied to the same university - she was about 5/6 years older. She kept saying that my a-levels wouldn't be as good and I wouldn't get in. Or if I did get in that I'd just drop out anyway. My cousin got BBB (which was the requirement when she came) and I got A*AB. She dropped out after 8 weeks, I'm 2/3rds of the way through my second year.
I can't say I've had that problem with my parents, they never went to university, my mum only recently got GCSE maths. But you do just have to remember its your life. If you want to switch just do it. If they say anything then you just have to try and shrug it off and keep going.
In the long run you'll probably end up proving them wrong anyway by doing incredibly well in a field you love - exactly like I did with my auntie and my female cousin, although she compares me to her son - even though he graduated with a low 2:1 and I'm target to probably get a 1st.
But you'll never even have the potential for this opportunity if you don't try. Its your life, nobody should have any say except you!