Hair genetics

[JisthenewK]

My mum has naturally brown hair, so does my dad. Her hair was actually blonde when she was younger. In her teen years, her hair naturally became darker until it was brown. Anyway, my brother is a redhead and I am a natural blond (brunette, now that I dyed it). So if anyone knows how to explain my mum and dad both being brunette and having two kids of different hair colours, please tell me why.