No more so than having a natural (biological) brother. I've talked with many host parents who have hosted students that were the same sex as their own kids (along with parents that hosted students that were of different sex). Some say it's weird for a boy to want to host a girl (or a girl wanting to host a boy). The mere fact that the student is the same sex doesn't seem to be a factor. One host mom talks about how they had to move their student into the bedroom of her own son for a week or so while family was visiting (I think they got bunk beds for the boys). When the visitors left, the student and her son decided they were in no hurry for the student to move back into the other bedroom. Another host mom says things have gone really well, it's just funny that the student and her own son are getting a little competitive about girls (fortunately, not the same girls).
My husband and I have hosted 5 exchange students; 4 girls and 1 boy. We don't have any kids of our own and a couple of our kids (to us, our kids, to the rest of the world, the students) said that they thought it would be 'weird' to not have siblings - until they got here and built a relationship with us. Everyone has their own idea of what's weird.
I can't guarantee that there won't be any awkward moments (especially in the beginning), but I doubt that any of them will have to do with you both being boys.
I hope your family does decide to host - it's a great experience! Feel free to email me (DamEngineer@msn.com) with more questions. (Note, Yahoo! Answers limits the length of messages sent via their message system and I can never say everything that I want to say in that length :) , so if you send a message via their system, my answer may have to be split into more than one message.)
Good luck to you!
I am a 5-time host mom and volunteer with YFU