By default the settings are
Show ads based on user interest categories. Visitation information from my sites may be used to help create interest categories.
Ive changed it to
Do not show ads based on user interest categories. Visitation information from my sites will not be used to help create interest categories.
I'm not sure I like that idea that google will be tracking every site I visit, and then when I do visit a site that displays google ads, it will serve me ads based on previous sites that I've viewed.
I cant do much about google tracking users, but I can do my tiny bit to ensure that my site isnt part of their targeting.