Q. I am the grandmother of adorable 2-year-old twins — a boy and a girl — who have distinct personalities and a bad case of the terrible twos.

They are loving, intelligent and inquisitive, however, and their parents are attentive and do many interesting things with them. They also have many play dates, age-appropriate toys and educational experiences, and are enrolled in a toddler music and movement class.

The father, who is a doctor, is quite involved, and the mother, a trained professional, is a very patient stay-at-home mom. She reads to them daily. She takes them to the library for story time and books. She has them help her put away laundry and make simple recipes. And her routines, discipline and schedules are sensible and consistent.

Nevertheless, the twins have become quite trying. They have meltdowns at dinnertime, especially when guests are present — even when these guests are children, too — and they resist their parents a lot, particularly at naptimes and mealtimes.

(Hadley Hooper for The Washington Post)

These children seem to feed off each other and become quite playful and silly, and then they push each other, cry and create general chaos. I realize that much of this is normal at this age, but this kind of behavior, multiplied by two, exasperates their mother. I kept the children at my house for three days last week and experienced the same problems, so I need advice almost as much as she does.

How can we bring some calm into the household again?

A. The twins may have a good routine, a good schedule and good discipline, but you’ll notice that most of their misbehavior follows one of two patterns. They fuss at naptime, as 2-year-olds often do, but that’s because they’re tired and because nature wants them to be as independent as possible at this age. That’s their job.

They probably fuss in the evening, however, because 5 to 7 is Arsenic Hour — that time of day when parents think they might like to take a little arsenic (or give it). And all because their blood sugar has dropped a bit and their children’s blood sugar has dropped quite a lot. Many parents forget to eat some protein in the mid-afternoon and only give their children a few cookies and maybe a piece of fruit after their nap. This is a mistake. Both parents and children need some protein in mid-morning and mid-afternoon because protein stabilizes behavior better than anything else.

However, the children may misbehave for company dinners if they are being served a little later than usual. A 15- to 30-minute wait — and the chance to show off for visitors — can send many children around their emotional bend. If that’s the case with your grandchildren, you can expect them to act much better if they’ve eaten half a deviled egg or a few apple slices smeared with peanut butter after their naps and a chicken nugget or two a half-hour before the guests arrive.

They’ll also behave better if their parents sit them down beforehand and tell them, firmly and seriously, that they have hired a new sitter for the evening and that she never puts up with any foolishness. She will stay in their bedroom, they’ll be told, but the first twin who gets rude or loud or difficult will have to stay with this sitter the rest of the evening. And if the other twin falls apart, they will hand her over to the sitter, too, and there they’ll sit, like two little lumps of coal, until it’s time to go to bed in separate rooms — and without a bedtime story. And yes, this is a harsh correction, but just the knowledge that a no-nonsense sitter is waiting for them is often enough to make children behave. If not, the children will probably shape up in a night or two with her because her style is still so new to them.

A little distance should help, too, whether or not company is coming. If the parents separate the twins for a little while each day, they won’t rev each other up so much. A 12-year-old neighbor can stroll one of them around the block while the other one runs errands with Mom.

Although this couple probably has one or two of the few books that have been written for parents of multiples, you might give them “The Art of Parenting Twins,” by Patricia Malmstrom and Janet Poland (Ballantine, 1999), and “Raising Twins,” by Shelly Vaziri Flais (American Academy of Pediatrics, 2009). Maybe one day they’ll even have time to read them.

Questions? Send them to advice@margueritekelly.com.