Adult/Child determined by age

Hi,

Is it possible to have a field on a form called ‘GROUP by AGE’, and have this field automatically populated from the value placed in the date of birth field. So if for instance the date of birth is 10th June 2010 then the person is 11 years old, so the value in my ‘GROUP by Age’ field states CHILD. If the value in date of birth field is 10th June 2000 the person is 21, so the value in ‘GROUP by Age’ field states ADULT.

Any assistance will be greatly appreciated.

Denis