The Boys' version of the X-Men features a handful of hilarious, dark parodies of their Marvel Comics counterparts. However, in the comic, the G-Men have a much darker origin that's based around one giant secret: They're part of a sex cult and were abducted as kids and abused by their version of Professor X.
In The Boys' universe, the G-Men are the biggest superteam in existence, with more than 80 members spanning across at least seven different teams - among them, the bigtime heroes with the G-Men, with lesser heroes part of G-Force, G-Style, and G-Wiz. The group features clear parodies of Wolverine, Beast, Colossus, and other iconic X-Men heroes. However, how the team was formed and treated is completely depraved.
In The Boys #29 by Garth Ennis, Darick Robertson, Simon Bowland, and Tony Avina, the titular group manage to confront one of the Supes associated with the G-Men named Jamal after Hughie joined one of the lesser teams to gain information. That's when he reveals that John Godolkin, the G-Men's Professor X, actually abducted kids at a young age and gave them Compound V to make them heroes. More disturbingly, he reveals that Godolkin sexually abused the children in his care.
The reveal leads to one of the most twisted moments in the entire series, as the G-Men and all of the teams gather in front of the G-Mansion and tell The Boys that "there isn't one of us [who] said no!!" to Godolkin's abuse. They also state "that there isn't one of us [who] won't die for John Godolkin." That's when James Stilwell from Vought American shows up and tells Butcher that he "we can clean up our own shit," as all of the G-Men are massacred with a wide array of bullets, bombs, and fire. It's a gruesome scene.
The G-Men are somewhat sympathetic figures, despite their depravity. When they're first introduced, they seem like sex-crazed maniacs. However, the revelation that Godolkin abducted and abused them somewhat explains their messed-up adulthood. The Boys' Amazon series based on the comic is getting a spinoff that's said to focus on the G-Men, however, thankfully, it's only loosely based on the group from the comics. It's completely the right move to avoid this storyline and adapt the characters more than their origins. Even for The Boys comic series, which is never shy about being gross for the sake of it, the G-Men's backstory is particularly screwed up.