Nope.. well for example.. 
I am 21 - Driving 3 years, 1 years NCB, 1 accident
Sister is 19 - Driving 2 years, 1 years NCB, 1 accident, both mine and my sisters accidents happened last year.. 
same insurance group car 
Yet I am paying 150 to 200 
more than she is! I couldn't believe it! 

Sucks to be a guy sometimes!
Jay