Any words for dealing with a 15-year-old who is verbally demeaning to his two younger sisters — sometimes abusively so?

Yes. Stop him.

The sibling bond can be bent, twisted, hammered and still hold. But why allow it to be so tested? Because a relationship can survive a battering doesn’t mean the battering is good for it. I might stagger up after a face-first fall down a flight of stairs, but the fall isn’t healthy for me.

Parents often permit some sibling-on-sibling maltreatment because others — experts, family, friends — opine that it is to be expected that siblings will argue, clash and even abuse one another. Indeed, some expert types posit that it is developmentally good for sibs to tangle, as they will learn much needed conflict-resolution skills. I wonder if such experts were “only” children.

Put another way, many say: “Don’t worry. While sibling bond may take a real licking, in the end, it’ll keep on ticking.” I say: “Such a licking usually only leads to a ticking off — of all parties.”

A verbal licking is particularly hurtful coming from an older sibling. A big brother or sister enjoys a natural status in a littler one’s eyes. He or she is seen as grown up, or a role model or even a protector. Yet even this intimate relationship can be fractured by an older sibling’s disdain toward the “lesser beings” of the family.

Indeed, the damage done can be measured by telltale remarks from the younger ones: “He’s such a jerk.” “Make him leave me alone.” “I really like it when he’s not home.” “Does he have to come along?” Sure, some of this stuff is said by almost all siblings sometimes. But it’s the number and emotion of such laments that reveal the degree of resentment.

What’s worse, sometimes the older child’s tormenting is aimed laser-like at the younger one’s most sensitive spot: appearance, intellect, grades, weight.

So back to my first words: Stop him. But your words alone won’t even slow him down. You need action, firm and certain. Levy a consequence commensurate with his meanness. If you believe your son is really nasty to his sisters, and you seem to, make sure your discipline reflects this. Possibly a full-day loss of all privileges for any mistreatment. A 1,000-word written apology. Doing all of a sister’s chores for three days.

Is your goal to stop this in its tracks, or just to tone it down to “normal”? Normal still implies some level of mistreatment is allowed. Is this what you wish to communicate not only to him but also to his sisters?

In the short term, you probably won’t alter your son’s attitude toward his sisters. That will take time. But you will alter his conduct. Your son won’t give vent to his disdain so freely, and your daughters won’t have to hear it.

This alone will help heal some of the fraying of the relationship.

When a child isn’t permitted to be nasty, he has two options left: Either he ignores his sibling or he acts nicer. Fortunately most kids learn to be nicer. Call it the pull of the sibling bond.

Dr. Ray Guarendi — psychologist, author,

father of 10 — is online at DrRay.com