Aptorian, on 08 April 2019 - 11:51 AM, said:
Could be he has a condition which I know as 'concave chest' (not sure what the official medical term for it is). Not sure how common it is, but around grade 7 (or there about), there was a boy in my P.E. class who had it. I remember the first time we played a 'shirts vs. skins' basketball game, everyone was kind of taken aback by it (the kid was really skinny so it was quite pronounced), and we were scared he would get hurt. The P.E. teacher explained the basics about it and that he would be fine playing basketball.