Is my brother going to be a late bloomer?

He is 18 and 5"5. His voice still hasn't fully deepened and when he works out his musceles still do not look fully developed at all. Like when he works his chest, it caves in and it never really goes out xD it's kind of funny. He also doesn't really ever shave because he never grows a beard. I am 17 and 5"7 yet I shave frequently every day and I am very hairy. I've got hair in my crotch area that extends all over my legs as well and I no longer get acne so I think I'm finished. This worries me because I am just barely 5"7 and I still want to grow, and I'm afraid my brother is a late bloomer and will pass me up and leave me as a shorty in the family :,(. What do you think?