I know this will come off as an obvious statement, but I had quite an epiphany (because it's all I can do on the overnight shift...).
The one constant is that we have all had contact with diapers directly, either by physical contact or close proximity; not by advertisement or media form. For most of us we've stated that we've noticed this connection in either one, two, or both age stages: 4 to 6 years and ~8 to 14 years of age. Even though diapers are not always considered a sexual outlet to all of us, the connection to them seems to touch on the two key areas of when body produces vast amounts of hormones (i.e. puberty) combined with ease of access to such devices (family daycare, younger siblings, etc.).
Lastly, I'm not posting this in order to kitty corner any one of us. I'm more interested in the psychological connection to physical properties around us as a whole.