Maris Otter isn't that old,being introduced in the mid 60s, and certainly younger than Fuggles and Goldings. Incidentally the dwarfing gene in Golden Promise spring barley,favoured by some crafties,arose through exposure to gamma ray radiation. I think it's an urban myth that germ plasm was exposed to an actual atom bomb,(how far away?),but I've heard that in relation to sweetcorn as well.