I've discovered that it takes most of your life to learn how to be a mother and a daughter. Perhaps it's being a grandmother that brings clarity.
I do know that there has been no role in my life more important that being a mother to my children. And it is probably that intensity of feeling that makes the job more difficult. My adult "kids" have told me that I was too controlling. I think that's probably true. You have so much invested in your own children in terms of love, emotion, caring, worry, not to mention food, clothing, shelter and education! They are your major project and you want them to turn out well, for their own happiness but also for your own sense of accomplishment.
As a daughter of an aging mother, I still struggle to relate to her, because our lives, while connected, are so different. This gives me insight into my relationship with my daughter. Her strongest bond moves down the generational chain, to her children, my grandchildren. It is as it should be.
Ah, grandchildren. Here I can experience unconditional love without the burden of "investment". We can just enjoy each other. It's one of the greatest gifts of motherhood.