Our pediatrician let us know when he was an infant that it was mostly a cosmetic situation as long as the organs had enough space to operate regularly. Usually, children become worried about it in middle school when the depth of the chest can actually worsen due to the adolescent development. The operation to fix it, currently includes putting a rod made of metal into his body to bend the chest back out over a lengthy period of time (12 months or so), and is recommended to be done between age 12 and 18 for children with moderate to severe indentation, which doesn't sound fun at all.
But he's not the only one with some kind of chest deformity. Since I lost my weight, I've noticed that my xiphoid process sticks out and is crooked. I'm going to blame the crookedness on X-man and his giant feet pushing at my ribs every moment of every day from month 7 of my pregnancy on because I have no memory of having it protrude before, but when I lie flat on my back, this nub of a bone sticks out. Kind of like how I discovered when doing pilates that my coccyx is a bit wonky and pointing out (I'm going to blame that a little on X-man and his giant infant body, too), which makes certain exercises difficult or too painful to do. But other obese folks have also written that after losing a lot of body weight, theirs started sticking out, too. The idea being that the excess fat might have also helped push that part of the cartilage forward.
I don't have a neat o'keen photo of my chest condition (and even if I did, I probably wouldn't share). So I'm going to use this lady with like zero percent body fat. I have no idea who she is. And please don't think that anything on my body looks anything like hers, particularly in a bikini, other than the fact that her XP sticks out as much as mine does. I wonder if it hurts her to lie face down on a yoga mat, too?
X-man understands that everyone looks different, and that being different is what makes us special. But he also understands that children have a tendency to point and stare at what is different. He knows this, because we've had to have the conversation about being sensitive and not blurting out comments about how someone is different even to ask questions. (Calling a man a she for having long hair, asking questions about why a man looks pregnant, asking why someone's legs don't work when they're in a wheelchair, etc. He can ask all the questions he wants when we're alone together. ) I'm hoping that by getting pool passes this summer, he'll grow more comfortable with his own body. I'll probably still have him in rash guards most of the time, just simply because I did marry the whitest man in America, and he totally passed that virgin snow skin onto our kid, but at the same time, I'm going to see if I can get him out at the pool for swim lessons without the guard, and work on some self acceptance.
So if you see his sunken chest or my sticking out xiphoid process at the pool from my (hopeful) attempt at wearing my first bikini this summer, please don't stare at our chests.