That's what I thought, and wrote. Now, if Mom had an Index of 20, and good son had an index of 20,and both played from the blues she'd get some strokes because the course rating/slope would be higher for her (as a woman) than him, therby giving her a higher handicap for that day. Correct?
Nope -- when I say "handicap", I mean handicap index. It doesn't matter what course or tees you compute it from, the HI is the "neutral" number that is used to compare golfers to each other. If Mom usually plays the red tees and Son usually plays the blues, then Mom probably is scoring lower per round than Son if the HIs are equal (assuming that reds have a lower rating [almost certainly] and slope [typically]).
Now, if both typically shot 20-over from their usual tees, Mom would have a higher HI because she plays the easier course.