BindingSource updates/reads all bound properties on a form when only one property changes using INotifyPropertyChanged event

Question

I am uisng Bindingsource in my app to bound my Business object properties to controls.I have implemetned INoTifyPropertyChanged in BO class so whenever the control's value changes it will update the BO property and same will be reflected to the control.I am facing propeblm when one property changes it tries to read all the properties binded to BindingOSurce which is really unnecssary as y shud i refresh /update the other propertites which are either read only or not updated.Can somebody let me know y bindingsource is reading all the properties.