I watched for an hour or so when my wife and daughter were doing the riding portion of the MSF. My wife, in her early 40's at the time, had no problems at all using her twist-and-go 125 Vino. My youngest daughter, then 17 or 18, picked up on shifting and riding right away. There was at least one, if not more, that had to completely drop out of the class. I watched one lady who could not ride a Suzuki GZ250, a Honda Rebel look alike. She just couldn't do it. She dropped out about halfway through the first day of the outside riding portion of the course.
When speaking of family members, unless you've trained them on offroad motorcycles or ATV's, or let them ride your own motorcycle, you really don't know what they can or cannot handle. Finding something a little less powerful and lighter is certainly hedging your bets some. Could it end up costing more? Absolutely, but then the end result could be that the person in question is a better rider for it.