Amazon.com's recommendation system
So in my ongoing search for comfortable shoes, I've bought a pair of Keen mary jane shoes from Amazon.com. Apparently those shoes trigger Amazon's recommendation system in particular ways. All of a sudden, my recommendations have turned into green Mommy recommendations- environmental baby products and so on. That one purchase triggered a construction of me as a particular kind of upper middle class, environmentally conscious mommy, even though none of my other purchases have ever indicated any children of my own.