When boys reach their teen years, one of two things usually happen: (1) they stop reading altogether, or (2) they make a very early jump to adult reading. Today, this is largely because the majority of YA fiction doesn’t cater to the male audience, either turning them off or driving them to join the adult audience.
At 13, my son reads above the college level (at least that’s what the school’s testing says; I say it depends on the day). He’s not limited by ability, but I don’t want him to miss out on literature targeted to his age group. And of course, there’s a lot of “adult” literature that’s too intense for him. He can handle the occasional violence and sex that can distinguish adult literature, and he’s interested in some of the adult-experience themes (work, marriage, horrific evil, power and corruption), but I think constant adult-level reading would be overwhelmingly intense for a 13-year-old. So, I work to balance it with carefully curated YA literature.
It’s not easy. I read a lot (1-2 books per week, probably 75% YA because that's what I write) and I still don’t feel like I’m aware enough of what’s out there appropriate for teenage boys. I read everything recommended for teenagers and I seek out YA fiction with male protagonists. I also encourage both of my sons to ask their teachers for recommendations (and sometimes I ask them myself)—teachers are a great resource, and they love to be asked (and appreciated).
Most people don’t have that kind of time, even if they were interested in all the reading. So you can use my Books for Boys recommendations and encourage your teen boys to read from this list, curated just for them.