Alot of this is cultural and "taught" when you are young.
I will give you an interesting example. I am Greek Orthodox. At a Greek funeral there is part of the service where you can visably see who is and who is not a Greek (no matter what they look like)--I WISH this had been in My Big Fat Greek Wedding.
At a Greek funeral, people line up to kiss the person goodbye. When people start doing this, you can visibly see the other people that are not used to this start shifting uncomfortably in their seats not knowing what to do...they are afraid of the body and would never ever even touch the person much less kiss them!!
In the US most Greek Orthodox priests will say something like, "It is our tradition to do this... If you feel uncomfortable please do not feel that you must participate, ...However, we have nothing to fear from the dead only the living".
But this is very much a culturally "taught" thing. Those children whose parents do this dont think anything of it.
I think part of this is all the horror movies in this country. The walking dead, etc. etc.
Just remember..you have nothing to fear from the dead. Only the living!! The bodies are there for you to learn. Some were just unclaimed but others were people who believed very strongly in helping science.
Oh, at a viewing we have a shot glass next to the body and you toast the person. Also, you get to have your photo taken if a relative. I know it seems a bit odd but not really.