Yup, welcome to Yaoi Land. Anything's possible :)
I'll suspend my disbelief for quite a bit, but that just looks silly...
LOL. When I was 15 there were two boys in my class. One was 2 meter tall and the other was around 160 cm tall (the poor guy only attracted 11-12 yo girls and he hated each and everyone of them). They didn't have that big a body size difference as they do in that picture.
Well, the other is too small, and the other is, well, too big XD
This is supposed to be a 16 yr old next to a 17 yr old? http://www.mangago.me/read-manga/ossu_ren_ai_gakuen/mf/v01/c002/23/