Here are some things to consider before considering purchasing a firearm.
Is he trustworthy and responsible with a proper demeanor? I would not get him a firearm if he has a short fuse, has a bad temper, is careless or irresponsible or does not think things through before acting or reacting.
What are you gong to do for firearm storage? Are you allowed to have firearms where you currently live? Is there someone in the house with a felony or domestic battery/assault charge or conviction?
Is there a shooting range or gun club in the area with prices you can afford?
It sounds like a firearm is something new to the family. Does the family have the funds available for proper training? The NRA Basic Rifle Shooting Course is one such course. Here is a link where you can do a search for this course in your area. Choose from the Basic courses on the LEFT. Courses on the right are instructor level courses.
http://nrainstructors.org/searchcourse.aspx
Is he right eye dominant or left eye dominant?
Regarding a first firearm, I recommend one chambered in .22 Long Rifle (.22LR). Be aware there are numerous .22 caliber firearms that are not .22 Long Rifle. The ammo cost for a .22LR is the lowest you will find for a firearm, and it has low recoil which is great for working on proper shooting form and techniques. IMO, they are also fun to shoot. I have several .22LR firearms in rifle and handgun platforms. For a rifle, I would look for a rifle in .22LR that is either a single shot with iron sights (scope not needed) or a bolt action with a detachable (removable) magazine with iron sights. I do
NOT like firearms with a tubular magazine or a semi-auto action for new shooters. I would suggest choosing one from a reputable manufacturer like Savage. Here is just one possible model. You should be able to get new less than MSRP.
http://www.savagearms.com/firearms/model/MARKIIF
Purchasing used CAN be a good option, but you need to know what to look for in determining that it has not been damaged (firing pin, chamber, barrel, rifling, trigger, etc.) or the trigger has not been altered or modified to be unsafe.
I again stress taking a firearm safety course as there are numerous things you need to know or learn. The dangers of ricochet is just one of these areas. Also be aware that BB guns, pellet guns, air guns - any type of firearms are not toys. The .22LR is not a large cartridge, but many beef cattle (some over 2,000 lbs) have been killed for butchering with a .22LR.