If you are a mother, then you know it is a central part of your identity. From the minute your first child is born, there is an invisible rubber band that links you to them  forever. You remain consciously and unconsciously tied to your children, always aware of the distance and space between you, like a psychic map always operating in your internal Google navigation app.

But the band remains flexible, stretching, shrinking, bending around corners, and as your children  grow, the operating system linking you to them n must sleep, but it never entirely shuts down. They are literally experienced as part of you, as brain imaging studies have proven. Photos of your children light up the same area of your brain as photos of yourself.

When my first daughter was born, for example, I noticed a change in my shopping habits. I was so gratified by buying things for her that my attention to myself diminished. Though partly due to ambivalence about my lingering pregnancy weight, it was also a reflection of the profound expansion of the sense of self that takes place when you  become a mother.

Little girls get bigger, and their sense of fashion kicks in faster than I could have imagined. As their personal sense of self evolves so do their choices. One of my daughters fell in love with everything pink, sparkly, and shiny by age four. Another preferred dungarees and the shoeless look, an urban Tom Sawyer. She had a strange love of “falling” in the water fully clothed, too. For the last day of school each year, the girls were required to wear a nice dress, and I learned to start the ever-contentious negotiations months in advance.

Yet the paradox of parenthood is that while this overarching connection and investment in your children is essential, being a good mother also requires that you let them become themselves. If your “rubber band” is too tight, it will snap. The process of development creates a unique double bind: you fall in love with your children, totally, and then you must spend the rest of their lives preparing them to leave you.

The children feel the urge to separate, and their anger and fear of this creates tension, as in the terrible twos, and the trying and sometimes terrifying teens, when conflicts reach a crescendo. I always knew that teenagers push their parents away, but it was not until I became a mother of one myself that I recognize that parents do this too. I saw myself become more critical of my child than I wanted to, and suddenly understood better why my father was so hard on me in my teenage years, even though I was not a very “rebellious” type. Parents also “push” their children away. It’s the natural order of things: we must force them to fly, but the pain of loss makes us angry too.

Mothers and children spend a lifetime negotiating the vicissitudes of this passionate bond and the degrees of separation necessary for independent, productive adulthood. Mothers of daughters are apt to identify with them and resisting narcissistic investment is a special challenge for us. And since society is more tolerant, even encouraging of closeness between women, we can remain intimately involved in or daughters’ lives.

For better, and sometimes for worse. Some daughters never feel the urge to separate from their mothers, but for others it is a continuous process. At each developmental milestone, another breach occurs: nursery school, camp, college, marriage, etc.