Bad and even dangerous advice, I might add, although neither uniformly bad nor uniformly dangerous. The author’s general suggestion is to let them be to work it out themselves, and/or to treat (or punish) them equally, which is actually quite common advice [emphasis mine]:
Siblings offer early, on-the-job training in how to work and live with other people. They also provide a crash course in how to manage intense emotions: envy, hatred, anger. In children of all ages, but especially younger children, the urge to compete for parental attention is innate. Among teenagers, sibling conflict helps them work out their need to differentiate from family and to set their own boundaries. Overall, research suggests the benefits of sibling disagreements include increased skills in understanding others, negotiating, persuading and problem solving…
When it comes to sibling conflicts, there are rarely innocents. For the most part, kids who are hurting one another or getting hurt, physically or emotionally, were already doing something you’ve told them not to do, and you won’t know the truth until they’re giving the toasts at one another’s weddings.
When all you know is that he said and then she said and then somebody did something and then there were tears, try this: Treat them equally. If there’s an injury that merits sympathy, gather everyone up. “Oh, that must really hurt where she hit you. Oh, you must have been so mad to do that. What can we do to make things better?”
Alternatively, if you’re just frustrated with the lot of them, take it out on everyone equally. “That’s it, playtime is over. You — empty the dishwasher. You — bring down the laundry.” If everyone involved feels terrible, you can feel secure that you’re on the right track.
All those things are good advice if—and only if—the fighting is the ordinary sort of sibling conflict in which relatively equally matched and pretty well-adjusted kids are squabbling. But are there really “rarely innocents”? There is another form of sibling fighting that is basically sibling abuse, and we don’t know its actual extent although it’s certainly not the majority of cases (we tend to think of sibling abuse as sexual abuse, which also exists, but I’m not referring to that).
It is often difficult for a parent to tell the difference between mere fighting of the ordinary type and abuse. Advice like that of the Times columnist, who is a parent of four—the sort of advice you’ll often see coming from “experts” as well—is dangerous if that advice doesn’t also include guidelines that help a parent tell when the squabbling is actually abuse in which a more powerful (either emotionally or physically or both) sibling habitually torments another sibling who is, in fact, innocent of any wrongdoing. The fact of the latter sibling’s being alive as a natural rival and irritant is usually enough to spark the abuse from the other sibling in these cases, rather than any behavior (much less any guilty behavior) on the part of the victim sibling.
That situation must not be allowed to continue; it is dangerous for both siblings, but particularly for the victim, and has the potential to leave deep and lifelong scars. “Letting them fight it out” and “treating them equally” is exactly the wrong thing to do in that situation; it tells the victimized child that there is no hope of rescue, and encourages him or her to blame him/herself for the cruel acts of others.
This topic was a particular interest of mine back when I was in graduate school, which was over twenty years ago. I did a lot of reading, wrote a long paper on the subject, and found that there was little to no discussion of the distinction at that time except for the paper I wrote. I’m pleased to see that a quick Googling just now has revealed a host of articles about the subject, so it seems that the state of knowledge and awareness has improved at least somewhat. But back then, I also designed a research project with a questionnaire aimed at uncovering and studying the difference. I never performed the research, although I probably would have, had I been going for a PhD.
In my quick look at the offerings now available online on the subject, I didn’t see anything resembling the research I had proposed. Most of the articles are fairly general. This seems to be one of the more informational ones. For example:
We need more research to find out exactly how and why sibling abuse happens. Experts think there are a number of possible risk factors:
–Parents are not around much at home
–Parents are not very involved in their children’s lives, or are emotionally distant
–Parents accept sibling rivalry and fights as part of family life, rather than working to minimize them
–Parents have not taught kids how to handle conflicts in a healthy way from early on
–Parents do not stop children when they are violent (they may assume it was an accident, part of a two-way fight, or normal horseplay)
In my own paper, I emphasized those first three points as key. The literature at the time stated as a given that children fight in order to gain parents’ attention and favoritism, and that is of course often true. But sibling abuse tends to have the characteristic of occurring most often outside the awareness of parents, so it certainly does not have the function of gaining parents’ attention. Its distinguishing characteristic is that its goal is to hurt (not necessarily physically, although sometimes physically) the victimized child, and the abusing child does not want to be caught and does not want the parents’ attention called to his/her actions. So naturally, the more the parents are away and the children are unsupervised or inadequately supervised, the more opportunity the abusive child has to harm the other child. And the more the two are blamed equally by parents for whatever fighting they do see, the worse it is for the victimized child, and the more blame he/she takes on in addition to the abuse.
The catch, of course, is that if much of the abuse takes place outside of the parents’ awareness, how would the parent ever know it’s happening? The articles I looked at recommend noticing behavioral signs such as nightmares, but those are relatively nonspecific. All I can suggest is to maintain awareness of the potential problem and to keep the lines of communication open, and also to be especially alert for it if there are marked differentials in size and age and personality between or among siblings. I would add “go for help to a family therapist,” but unfortunately many such therapists are not aware of the distinction and will give advice similar to that of the Times article, so be alert for that, too.
The illustration that accompanies the Times article is also typical of such “leave them alone” articles, because it shows equally matched siblings, which is so often not the case:

So, how common is such abuse? I’m not talking about single acts of sibling physical violence that are severe enough that they get reported to authorities as such (the only discussions I could find when I wrote my paper was of that sort of thing—for example, sibling murder). That link I gave earlier puts it this way:
Experts estimate that three children in 100 are dangerously violent toward a brother or sister. A 2005 study puts the number of assaults each year to children by a sibling at about 35 per 100 kids. The same study found the rate to be similar across income levels and racial and ethnic groups.
But “number of assaults” probably doesn’t measure what I’m interested in, either. It probably just is an estimate of hits, which is not the same thing as the incidence of physical and/or emotional abuse. I looked at one of the studies cited which is available online (see this), and it lumps in sibling assaults with assaults by children in general, so it’s not useful for determining the incidence of the phenomenon I’m talking about. I think it’s telling that, even among many researchers, the matter has been relatively neglected and/or minimized.
Interestingly enough, when I looked at the comments to the Times piece, nearly every single one I read was an objection to the article from a person who claimed to have been subject to sibling abuse that was unchecked and had serious negative repercussions for them. That certainly indicates a fairly high level of incidence, at least in the anecdotal sense.
