Why him but not me

well I come from a white family and I dont agree with racism in fact I hate it for everyone is human there is no difference except we all have our own uniqueness but the fact of the story is my mum and my Granda (to which Ive disowned) can be very racist at times but its not that my mum wants to be its just what shes grew up around and so my mum isnt that bad like my best friend is a person with different t skin colour to our family but we all love her so much she is honestly like part of our family we love her that much. Ive always been told by my Granda that Im not allowed to date a person of different skin colour and when he came to visit he would always tell me off when I would hang out with my best friend who is of different skin colour. My brother however dated my best friend and nothing got done about it he never got told off but yet when I got into a relationship with her I was yelled at I got took away from seeing her for 3 weeks it was hard but I dont understand why its different for me but not my brother it doesnt seem fair especially as a person is a person and love is love others shouldnt try to stop that. Anyway thats my story to this day me and my best friend are still like sisters even though we are miles apart now.