The thing I wondered was whether that was deliberate or not. Charles Duhigg talks about this in his book on habits. Target has the data to identify expecting mothers. Rather than bombarding strictly baby related photos, they careful include seemingly other unrelevant ads so it doesnt come off as intrusive.

Although I will say that in my own ad experience, the ads have generally been more related to my interests than this author describes. .

I thought I read something recently stating that the Target anecdote had been somewhat overstated. Unfortunately, I could not find the article I had in mind -- but here's a similar one. http://www.ft.com/cms/s/2/21a6e7d8-b479-11e3-a09a-00144feabd...

Choice quote:

Hearing the anecdote, it’s easy to assume that Target’s algorithms are infallible – that everybody receiving coupons for onesies and wet wipes is pregnant. This is vanishingly unlikely. Indeed, it could be that pregnant women receive such offers merely because everybody on Target’s mailing list receives such offers. We should not buy the idea that Target employs mind-readers before considering how many misses attend each hit.

In Charles Duhigg’s account, Target mixes in random offers, such as coupons for wine glasses, because pregnant customers would feel spooked if they realised how intimately the company’s computers understood them.

Fung has another explanation: Target mixes up its offers not because it would be weird to send an all-baby coupon-book to a woman who was pregnant but because the company knows that many of those coupon books will be sent to women who aren’t pregnant after all.

None of this suggests that such data analysis is worthless: it may be highly profitable. Even a modest increase in the accuracy of targeted special offers would be a prize worth winning. But profitability should not be conflated with omniscience.