The first thing I see when I look at this photo is my son’s mustache. It’s wispy but pronounced enough to show in a photo. I told him a few weeks ago that it’s time to shave.

He said, “Mom. You’re embarrassing me. Don’t talk about my body hair.”

So I didn’t bring it up again but about a week later, he said, “Mom, I think I need to start shaving.”

I said, “Okay” and we bought a razor. I told my husband we need to pick a time.

My husband said, “Okay. Whenever.” It wasn’t a big deal to him, but it must be a big deal to me because I keep putting it off. I don’t want this time—right before puberty—to end. I don’t want to lose my goofy, unkempt little boy.

I remember when my brother was getting his economics Ph.D. at University of Chicago. I used to think economics was so mathy and difficult. But he talked all the time about how unpredictable people’s bad decisions are. (He sent me this book to read, which I couldn’t read, but I liked having it on my shelf.) By the time my brother graduated I was much more conscious about how we all make irrational decisions (like we buy when we should rent).

Then I was giving a speech at a national marketing conference and by some miracle I got there early and listened to the guy before me, Dan Ariley. He studies how people make decisions. He tries to predict when we will behave irrationally.

His speech was great. He talked about the study of how we can literally miss a gorilla in the room. He showed how if there are too many choices for jam flavors we won’t buy any jam.  And from Airley’s writing I have concluded that I have loss aversion. Loss aversion means that our emotional reaction to a loss is about twice as intense as our joy at a comparable gain: Finding $100 feels pretty good, but losing $100 feels absolutely miserable.

You can apply this to making a career vs kid decision if you add the endowment affect. Behavioral economists use this term to describe how we place more value on what we have than on what we don’t have.

What’s interesting to me is that when women have a big career, they are less likely to say they plan to give it up when they have kids. Because they have the big career and they don’t have kids.

But when women have the kids, and the kids are growing up very fast and the women perceive that they are losing something, we start to value the kids more than their career. This is exactly my experience of kids vs career.

When my kids were young I did what research told me to do: breastfeeding, attachment parenting, and so forth. But I spent most of that time worrying that I was losing my career and tried to find ways to keep that from happening.

Then, suddenly, when the kids were six or seven, I noticed that my sons were growing up very fast. I saw that I missed a huge amount of time that I could have had with them. That time was gone and I couldn’t get it back. I also realized that I didn’t really have a huge career any more. I couldn’t keep up with twentysomething guys who slept in their office. But I did have two kids growing up right there, in front of me. And I didn’t want to lose that.

When I scaled back work to move to the farm, I worried that I was losing my mind. But in fact, I was acting the way behavioral economists predict I would act. And, not surprisingly, I was following in the footsteps of many powerful women. Women who love their jobs and the money and power that goes with their jobs do not quit work when they have kids. They try to hold on to work. I have noticed, though, that most of those women drop out as they become more attached to their kids.

Anne-Marie Slaughter, Michelle Obama, Brenda Barnes: these women had huge jobs, kept them when they had kids, and then when their kids were older and more independent, the women quit their jobs because they realized they were losing their time with their kids.

This is why most women who agree to having their husband stay home with the kids end up regretting it as the kids get older. We women scale back our work drastically to protect what we have: the opportunity to watch our kids grow up. And we are not so scared to give up the chance to get what we didn’t have anyway: the big career before we had kids.