O thanks, and why is that? is it because they being exposed to much from the nuke blast
from the wiki-
edit Biology Ghouls created in the Great War of 2077 were still alive during Fallout (2161), Fallout 2 (2241), and even Fallout 3 (2277). All ghouls live longer than normal humans. It has to do with cellular level, and the ability for some ghoul DNA to make more copies of themselves. In a ghoul, sometimes, additional genetic material is added[1]. The unnaturally long lifespan is also due to a mutation within the autonomic nervous system of certain individuals following exposure to specific combinations of ionizing radiation with wavelengths below 10 picometers. Radiation having such a short wavelength, less than 10 picometers, is known as Gamma radiation and is enormously dangerous to healthy humans. This mutation disrupts the normal process of decay in the neurotransmitters along the spinal cord.
Specifically, the transmitters affected are those responsible for cardiac and respiratory function in a healthy human. These transmitters are continually regenerated after mutation, carrying sufficient oxygen to sustain the life of the subject while being insufficient to retain skin elasticity and avoid necrosis, the result of which is the corpse-like appearance of post-mutation humans.
Ghouls are generally as intelligent as normal humans. However, their repulsiveness makes the life of a ghoul difficult at best - only the most tolerant human communities accept them as anything more than monsters. Some ghouls eventually go mad and are called "feral ghouls", giving all ghouls a bad reputation. These feral ghouls create the misconception amongst regular people that they are Zombies, only alienating Ghouls further.
Ghouls are, naturally, immune to radiation. Radiation poisoning can't really get worse for the ghouls. In fact, many ghouls now are gaining health in radiation, making their homes near locations with acute background radiation. The "Glowing Ones" actually enjoy large amounts of radiation, which they describe as being "comfortably warm".