growth in rabbits

I m new to owning rabbits. This is a wonderful site lots of info and great learning tool. my quieston is my bunnys are about 12 weeks old they are dutch and brother and sister and she is twice the size of her brother. was wondering if this is normoul ( spelling )
   
thank you

it sounds pretty normal maybe the female is just stealing all the males food, also are your rabbits neutered becuse they may start breeding soon !

thank you for your answer. They have a vet appt on the 23 of july to be fixed. My vet wanted to wait until they about 20 weeks old. In the mean time they are in differant pins, and they dont like it much. Thanks again for your answer.