Why do ladies hide their age?

Age happens.  Nothing we can do to stop it.  It happen by the year, month, week, day hour, second and millisecond.  As I celebrate my 45th birthday today, I have to ask the imponderable that many are probably scared to……Why do ladies hide their age?  Why are they reluctant to answer the dreaded:  “How old are you?” question.  Why is it socially acceptable to NOT ask a lady her age and considered bad manners if you do?  When did it all start?  Well, I guess I’ll have to look into that one.  Lucky for me that my wife told me how old she was when we met.  I’ve been keeping track ever since so that I don’t have to ask