Father was old and sick. Kellogg was way older than him, but he still looks young and fresh when you get to see him. One could argue that this was because of the parts he had implemented. Why did they let father age in the institute. Ok, gray hair doesn't mean that one is old, but he clearly looked more than a 60 year old than Kellogg, who has to be somewhere around 100 minimum.
Is this explained somewhere or is this some kind of "hole" in the story?