There's a temptation to grab any headline with the news you want to hear—chocolate is good for you! So is coffee! And wine!—and stop reading. That's certainly a temptation for me when I see a study like this touting how great breastfeeding, especially extended breastfeeding is, for kids. I've got a lot at stake in this, having breastfed all of my five kids which, taken together, adds up to nearly eight years and counting.

Yet as I read the details of the study, I instantly see that I should be cautious in taking this as a settled issue. It's an interesting, long-term study, which takes into account and controls for many factors (income, education, family size, other health and socioeconomic factors, etc) that might skew the outcomes. But still, there is a potential selection problem and it is hard to capture all the factor that might differ between women who breastfeed and those who do not. And it could be that it is those other things, not the breastfeeding, that are associated with improved life outcomes.

And in fact, it's because those other, hard to control for factors are more or less taken out of the equation in this study—a comparison between siblings in the same family, in which one was breastfed and the other not—that I find it most convincing. And sadly, that's the one that calls into question all those long-term benefits of breastfeeding.

I hope breastfeeding is good for children. But even if it's not a miracle elixir, there are many reasons to choose to breastfeed: It is cheap, convenient, and a nice way to spend a lot of time snuggling baby. That's good enough for me.

But I don't want to let my personal stake in the question of breastfeeding's benefits to lead me to accept hyped headlines, especially since the debate about breastfeeding's impact is oddly politically charged. That means that I need to keep reading on and carefully consider what the study tells us, and want it might be missing.