I’ve heard of spontaneous pneumothorax as a problem associated specifically with Marfan’s Syndrome.
6’4" here (1.93m in new-speak). Yes, being so tall is a pain. Like kferr, fitting cars is very difficult - indeed, I meet up with a group of friends every year at the Goodwood Festival of Speed and we see if I can fit into any of the supercars; headroom and legroom are real issues. kerr, take a look at the Skoda Yeti, the Maserati Quattroporte, and the 4 door Bentley Continental. I have to be careful going down stairs - I once crashed into a light fitting at the bottom. I can spread my fingers on an 8’ ceiling when I’m barefoot. Such rooms with even modest light fittings are a navigational hazard; I really love rooms with 10’ ceilings! Driving is an issue: I have a large blind spot behind the rear view mirror and my eyeline is near the top of the windshield which means I have less time to react to traffic signals.
Maybe Sicks Ate will show up and tell us something.
Does he swim? Such a build is typical of swimmers.
I’m 6’5"-ish so I’ll add my two cents.
First, clothing. Buying clothing sucks and if you’re taller than me it is likely worse. Shopping online is a frustrating exercise because if you finds something you like, they won’t have it in your size (or they will, but only in lime green).
I only buy clothes that are well-made, from reputable long-lived businesses, and when they have things that fit me, I buy a lot of them. For example, the only shirts I wear to work are Lands End Hyde Park Oxfords. Every three years or so I wait for a sale and I buy 3 blue, 2 white, and either a pink or a patterned one.
I wear size 14 or 15 shoes, depending on the maker, and I buy only from Allen Edmonds or Alden. I’m wearing a pair of sz 15 black Alden cap-toe oxfords right now. They cost $460 when I bought them, which seems like an insane amount of money to spend on a pair of shoes, but I bought them seven years ago and expect to get at least another 3-4 years out of them. That’s $46 bucks a year.
I have a pair of LL Bean Maine Hunting Shoes that I bought 25 years ago! Still pull them out every spring.
I feel your pain, my oldest son is 6 and is projected to be “at least” 6’6. I hope for his sake he ends up a bit shorter than that.
I’m 6’4" but I would like to explain that not all tall people started that growth early (just so folks don’t think that if you aren’t 5’1" by 10, you won’t be tall). Your son is 5’1" at 10. I was 5’1" and 80 pounds at 16 (still have my first drivers license). I was about an inch taller at 17. In other words, I was the shortest and smallest guy in my high school class. 6’ tall at 18 and 6’4" and 135 pounds at 19. Try to find 29" inch waist pants with an inseam of 36". Beanpoles were fat compared to me.
6’4" isn’t tall enough to worry about hitting your head on most doors. A lot of older basements can be problematic. My biggest problem is airline seats. I have long legs (short torso - long legs. My bike fitters always bring this up). Someone just mentioned hitting their head going down stairs - that is a problem but at least you can usually see it coming.
Keep him swimming, if he enjoys that. Tall swimmers have the advantage. Think of Michael Phelps, who is 6’4". And his triangular build will fill in nicely as he develops muscularly.
Regardless, find out what he likes to do, and then encourage and support that. That willhelp him to grow to be a confident man.
I’m only 6’0" so I have no experience. My best friend in college was 6’6".
Also, teach him that his worst enemies in the world are low-mounted ceiling fans.
My forehead still bears scars from the one in my grandparents’ dining room.
My brother in law, who was 6’5", always said “They don’t make things for geeks.” He was always banging his head on things; sadly, it never knocked any sense into the asshole.
Knocking sense into that asshole was the job of his older brother(s), if he had any, and shoulda been done long ago.
He likes to watch YouTube videos.
He also does like to swim, but he’s not very good at that either-- on the other hand, it also took me forever to learn how to swim, but I eventually got really good at it.
He’s already frighteningly muscular for a prepubescent non-athlete. People ask if he’s in high school. He’s gonna be taller than the rabbi at his bar mitzvah.
He had none. My mother flattened his ass early in my sister’s marriage to him, and my brother was going to (literally) kill him on a hunting trip, but my father talked him out of it. More’s the pity.
Boychik is only, what?, 10? It takes a while for the coordination and also the brain to kick in for us guys. We’re always behind the girls, they mature faster than we do.
Well then, when it all comes together for him (muscular coordination, and the brain realizing Hey, I want to win!), then he will be a beast at whatever he decides to do. As long as he likes it, keep encouraging him.
As long as he likes it, that’s the key. And I hope you are being patient, loving, and supportive there, Mom. I believe you are.
May I share a little about my son? He is 30 now but when he was a kid he loved to dance. He did baseball, cello, boy scouts, theater, and soccer, but as grade school gave way to middle school and then high school, it turned out that dance was what he really loved. His mother and me, we’re not dancers. I’m a retired US Marine, for sakes alive, and I didn’t understand dance. I understood all the other things. But it turned out that his passion was dancing. He loved it, it turned out. He followed his passion, we supported him but he put in the hard work, and now he is a professional dancer living and working in NYC. Just last week he was on the cover of the NY Times! OK it was the Arts section. That’s him on the far left, and he’s also in the next picture.
The point here is that boychik will find his way. He may be tall, but if you help guide him towards activities where that is an advantage, then he’ll already be ahead of the game. As the saying goes in basketball, “You can’t coach height.”
And there’s lots of good advice here by the tall folk who know what it’s like. Sorry for the lengthy reply.
Perfectly fine. Great post.
I’m really glad I started this thread.
Just out of curiosity, any parents of tall boys have advice on feeding them through adolescence?
Save now. Invest wisely. 
Buy large dishes or just use a bucket.
I’m not tall but in HS & college I was a skinny swimmer with a very high burn rate. Nobody could routinely out-eat me. I’m not talking showing off; I’m just talking my idea of a normal days’ calories was up around 3500. And not junk food.
In college I had a 6’3" roommate who rowed crew. He routinely ate double what I did. It was horrifying to watch the food and money go down that maw. His standard breakfast was a half pound of bacon, 6 eggs, and half a box of cereal with a quart of milk. And 3 apples or oranges.
My best advice is to bring plenty of money. You’re gonna need it. And a bucket.
The height thing I don’t think will really affect how much he eats. My 6’6" son didn’t appear to eat much, and I have a 6’7" nephew who was similar. Both athletes also, but didn’t eat any more than their shorter brothers.
Of course any teen boy is going to eat, but I don’t think height has a lot to do with it.
When my husband was in high school he was on the swim team and I asked him about how much he ate: he estimated about 4500 to 5,000 calories a day during the season and somewhere around 3500 off-season.
He drank between a half and three quarters of a gallon of milk almost every day. I personally know that he would routinely order a large pizza in college, just for himself, no leftovers, no sharing. He is not a broad man: he wore 32" waists at that time.
He suggests lots of pasta and buying a bread machine.
My pediatrition gave this definition:
Teenager: [teen-ey-jer] N - Def: an appetite covered by skin. :eek: 
Me too; & I hate houses with taller ceilings. Not only can I not stretch my back out (by getting resistance w/ my hands on the ceiling) but I need to get a @#$%& stool to change a light bulb. :mad:
As previously mentioned, Big & Tall stores are just that Big & Tall, not Big or Tall; Lands End / LLBean will be his (your) friend.
He’ll learn to duck, particularly on basement stairwells. Most lower lighting fixtures are over a table, so standing up after eating will be an issue but otherwise not so much.
Let me also add proportionality is a component of it; three guys may be the same overall height but hip height can be different; one has longer legs (& needs a car with more leg room) while another can have a longer torso (so roof height & not leg room is the deciding factor when buying a car).
One thing I haven’t seen mentioned yet - slow dancing. Do you know how many couples I’ve seen slow dance cheek-to-cheek, with his chin on her shoulder. His chin on top of her head is NOT nearly as romantic, & bending over/squatting isn’t comfortable.
On the plus side, it’s easy to navigate quickly thru a crowd; a tall person can see openings & know whether to juke left or right to go faster than the average speed. This is great when, say, leaving a concert.
Low
Medium
The nutritionist recommended 6-8000 calories a day for mine.