Parents of multiples know that raising twins is about more than just giving the same number of gifts on their birthday (although that is important).

From feeding two newborns who are both hungry at 2 a.m. to sending them both off to college at the same time, parenting twins is challenging. Perhaps no time is more challenging than when they are teenagers.

As a father of teen twins (along with two other singleton teens), I can offer these reminders.

1. They are not schizophrenic, they are establishing an identity

Of course, this is true for all teens, who sometimes struggle to differentiate themselves from their parents and family unit.

But for twins, it’s also about establishing independence from their twin. This starts before the teen years, but may accelerate during this time. For many twin couplings, the teen years may be the first time they are each pursuing different activities, sports, clothes, hairstyle, makeup, friends, and beyond.

This is easier for mixed gender sets, but it can be a difficult time for all twin pairings.

2. Are you ready to rumble?

As your twins transition into teenagers, you may find them fighting more frequently and louder and more aggressively. And it’s usually over something trivial.

Then two minutes later, they can be best friends. This “push me, pull you” behavior that parents witness with a teen singleton is now doubled. They act that way with parents, but also with their twin.

3. They are expensive

This has always been the case, but now the objects they desire cost way more. Think: Two prom tuxedos or dresses, two sets of braces, two new drivers on your car insurance.

And at the end of this teen period, two college tuitions at once. Vital organs, like twins, come in pairs, which is helpful, since you may have to sell a kidney to afford all this stuff.

4. Be prepared for drama (or the lack of it)

All teens have ups and downs, but it’s a little different with twins, because they aren’t always on the same wavelength.

When one is up and the other is down, it’s difficult for families to celebrate the successes and console the setbacks. On the other hand, they both may be up and down at the same time, which may be worse, since they both may be screaming at you at the same time over different issues. And you thought the 2-year-old tantrums were bad!

Some teens show a remarkable lack of drama, issuing mumbled monosyllabic answers to all your questions and spending their free time in their room or at a friend’s house. If you have two of those, it can be frustrating. Buckle up.

5. Twins may have very different academic abilities

Parents of twins know that they each have their own strengths and weaknesses. But the stakes are raised as teens, as their academic achievements in high school may put them on different paths in life.

Even identical twins may have very different grades in school. Parents need to be ready to deal with this. Like all parents, parents of twins should encourage each child to be successful in their own way.

6. Who is that woman, and what did she do with my baby girl?

Body changes are part of the teenage experience for everyone, but with twins, it’s double the fun.

If you have twin girls and one likes one type of “feminine product” and the other prefers a different type or brand, be ready for those 11 p.m. runs to the pharmacy. And no matter the gender, they don’t ever want you to see them naked anymore, and vice versa, which is appropriate.

And one more thing: zits. There is no cosmic injustice greater than that of one twin having smooth skin and the other with Mt. Vesuvius on the tip of her nose just before homecoming. Oh the humanity!

7. They stink

This is part of #5, but it deserves its own point because it is so important. Again, this is true of all teens. But if one teen stinks, two may cause your neighbors to complain. Their stink comes in two kinds.

The most obvious is the organic stink, the teen funk of body odor, sweaty feet, and unwashed hair that you can’t believe is emanating from your little angels. These teens need to be reminded to shower and actually use soap and shampoo.

The other kind of stink is the inorganic kind, usually a cloud of deodorant or perfume enveloping your twins who are apt to shower two or more times a day. Then you walk around in a haze of Axe Body Spray or Jean Nate perfume.

And the worst is when you have one twin who is allergic to showers and another twin who applies the deodorant by the barrel.

8. This too shall pass

Remember when they were getting up in the middle of the night? Remember when they were both throwing tantrums during their “terrible twos” at the same time? Remember when they each got the flu, and not concurrently, but consecutively, so it seemed like your house became a hospital ward for weeks at a time?

You got through all those stages, and this one will pass, too.

9. Consider yourself lucky

When our twins were younger, and we put them in bed, my wife and I would look at each other and say, “I wish I was a twin.”

Parents of twins are blessed. It’s a wonderful experience, and I hope you appreciate how special it is to witness and nurture that special relationship, even during the teen years.