Why does this happen?

This whole baby raising thing is filled with fears that you are doing the wrong thing. For example, just now I was just doing my best to finish a Sunday Times crossword (it is my goal to complete one before Emmett heads off to either college or the army) while Emmett was sleeping and Andrea was reading a book of what each week of Emmett's life should bring, and Andrea read aloud that one should never handle a reptile and then a baby as reptiles carry a very, very bad form of salmonella. Well, this week I have been watching the neighbors' pets and Emmett was a little fussy yesterday so I took him to their house on the one day that I had to feed their snake. Feeding the snake meant putting the snake into a paper bag with two dead mice so I set Emmett on the bed and touched the snake, too. Now, I do not like touching snakes or reptiles at all, and in fact I would bet that I haven't touched a snake for something approaching twenty years prior to yesterday, but as soon as you put a newborn in my hands I am Steve Irwin. I have been spending the time since Andrea's reading trying to reassure myself that I did, indeed, wash my hands immediately and that, either way, I only touched the snake with two fingers, but this seems to be yet another on the list of things that you only find out after the fact that you are not supposed to be doing. Why I wasn't told at Emmett's birth not to touch snakes I just don't know.