grammar lesson of the day

Capitalize Mother, Dad, and other titles if you can insert the person's name and titles like Grandma and Major when they appear with a formal name.

If you can replace the "mother/mom" or "father/dad" with the person's formal name, "Mother/Mom" or "Father/Dad" should be capitalized.

Example: Mother is really my best friend. 
Example: Donna is really my best friend.

If you cannot replace the "mother/mom" or "father/dad" with the person's formal name, then "mother/mom" or "father/dad" should not be capitalized.

Example: My father is really nice. 
Example: Fred is really nice.

In the above example when the father's name--"Fred"--replaces the name "father," the sentence does not make sensesuggesting that "father" is a general term, not a formal name and should not be capitalized.

from the nice people at Paradise Valley Community College, Phoenix, AZ