I am pretty lenient with my 14-year-old and he knows it - he tells me stories about other kids' dads. At 14-years old however, he lacks the discernment between the flexibility he is afforded, and other children his age who have overly-strict parents, yet are allowed to do things he's not allowed to. He struggles with this. I explain that every child is different, and ever parent is different, and between the two the possibilities are infinite.
One of the things I forbid is Grand Theft Auto. He doesn't quite understand because he's allowed to watch certain "MA" (Mature Audiences) rated television shows (Rosario+Vampire most recently) and play certain "M" (Mature) rated games (I let him play Diablo II when he was nine). I do understand where making exceptions rather than across-the-board rules can be challenging - many adults even have difficulty reconciling these things.
He asked me about it again today. "But why?" he begged. Rather than give him my opinion this time around, I got as specific as I could without injecting my own subjectivity - I calmly read him the following (without skipping anything) from the ESRB's site for GTA V (highlights mine):
In this open-world action game, players assume the role of three criminals whose storylines intersect within the fictional city of Los Santos. Players can switch between each character to follow his storyline, completing missions which often include criminal activities (e.g., stealing cars, executing heists, assassinating targets). Players use pistols, machine guns, sniper rifles, and explosives to kill various enemies (e.g., rival gang members); players also have the ability to shoot non-adversary civilians, though this may negatively affect players' progress as a penalty system triggers a broad police search.
Blood-splatter effects occur frequently, and the game contains rare depictions of dismemberment. In one sequence, players are directed to use various instruments and means (e.g., pipe wrench, tooth removal, electrocution) to extract information from a character; the sequence is intense and prolonged, and it involves some player interaction (i.e., responding to on-screen prompts).
The game includes depictions of sexual material/activity: implied fellatio and masturbation; various sex acts that the player's character procures from a prostitute—while no nudity is depicted in these sequences, various sexual moaning sounds can be heard. Nudity is present, however, primarily in two settings: a topless lap dance in a strip club and a location that includes male cult members with exposed genitalia in a non-sexual context. Within the game, TV programs and radio ads contain instances of mature humor: myriad sex jokes; depictions of raw sewage and feces on a worker's body; a brief instance of necrophilia, (no nudity is depicted).
Some sequences within the larger game allow players to use narcotics (e.g., smoking from a bong, lighting a marijuana joint); cocaine use is also depicted. Players' character can, at various times, consume alcohol and drive while under the influence.
The words “fuck,” “cunt,” and “nigger” can be heard in the dialogue.
It was an effective strategy; he admitted it was quite a bit outside his usual fare, having looked upon it strictly as a car game. I went on to say he didn't even understand everything I just read. He disagreed.
"Really? Do you know what necrophilia is?"
"Do you want to know? If you want to know, I'll tell you."
"I respect your decision. Let me know if you change your mind."