Your results, even when logged out, are heavily biased towards your previous query genres. For instance, I'm not logged in, but am at home with an IP address that hasn't changed in over a year despite being leased. When I search Google for the term "Ruby", the entire first page is for the Ruby programing language.

My father works with jewelry. Last week while visiting him, I did in fact search for the term "Ruby" on his computer in his normal browser, and even though he was also logged out, I wasn't able to find one result dealing with the programming language on the first two pages.