Being a mother is not just a 9 to 5 job or a birth to age 18 job. Maybe it should be, but some mothers, myself included, view it as a lifetime commitment.
It doesn’t matter how old their child is, if good old mom thinks they need a little discipline, a talking to, a scolding, she’s right there on the job, much to the detriment of family relationships. Mothers also have the ability to remember every past real or imagined grievance and bring it up months or years later. They are also the undisputed experts in the art of laying on the guilt trip.