There is a 50% chance of someone geting NF1 since it is a dominant trait Even if niether your mom or dad carry the gene there is still a 1/7000 chance you'll get Neurofibromatosis. The reason why there is a high chance of someone to get NF1 without thier family having NF1 is because the protien is so large and complex. For example if there was just one weak link in the chain it would break the entire chain.