The responsible thing is to figure out if there is something we can do to change this, to retain a larger number of female students who had already shown interest in pursuing a career in physics.
This presumes that the answer to your preceding paragraph is already known and the verdict is guilty. If this were true, I would be onboard with your quote. But I dont see it as true. At the risk of being some "Joe Schmoe off the street who simply has an uneducated opinion about this and decided to spew things off the top of my head", I see women and men turn away from science to their own benefit. Science is a career oriented profession and that is not fulfilling to them and they are doing great after leaving. I dont think there is anything wrong with women being more family oriented than men. I dont think there is anything wrong with that if its biological, sociological or a combination of the both. Honestly, I'm a little jealous of that now that I am nearing middle age. I probably could have enjoyed fostering and being with family instead of shooting for a career.
I think the women often have the right idea. Family can easily be more important than a career.
edit - I like your thoughts though, and appreciate them. They are better than the knee jerk guilt that I encountered so often in school.