The death-dealing Krogans from Mass Effect are usually clad in their full-body armor, but if players have been paying attention to the conversations that arise in the games, they would have realized all the way back in Mass Effect 1 that underneath that hulky armor are four testicles. It has now been revealed that this idea most likely came from Star Trek, in which Klingons have an extra set of vital organs.
Klingons are perhaps the most popular characters among Star Trek fans, with some people even learning the fictional language of Klingon. However, there are some things that even the biggest fans might not know about the Klingon race, and while it is fairly common knowledge that the esteemed warriors have secondary, redundant organs like an eight-chambered heart, a third lung, an extra pair of kidneys, and even a second brain stem, it may interest some people to hear that they also have three testicles and two penises. This inspired the developers of Mass Effect to give the equally war-mongering Krogans two hearts, a second pair of lungs, and apparently another doubled-up set of organs
In a recent TheGamer interview with Mass Effect 3's writer Chris Hepler, Hepler spoke a little bit about the nether regions of his characters. After watching more Star Trek, he says that he realized that the first Mass Effect team probably got the idea from the famous fictional Klingon race, and subtly added the unusual anatomy of the Krogans into a codex entry and a few throwaway lines. Hepler muses that the developers became more confident about it with each game, and by the time Mass Effect 3 was finally out, jokes and slang about the extra testicles were all over the dialogue, with Hepler pointing out lines like "not having the quad for it."
With this knowledge in mind, romancing a Krogan could be quite thrilling, for players who are into that kind of thing. Having an extra pair of lungs for increased stamina suddenly doesn't seem so frightening. The Mass Effect franchise is well-known for giving its players the option of romancing many characters in the games, several of these being aliens, and it isn't really a BioWare game without some sci-fi love role-playing.
The entire Mass Effect trilogy includes elements of roleplay where the player must make decisions and bear with the consequences. Fans were disappointed by the final game and conclusion to the story, but an extended cut was released for the game that helped resolve some of the controversy surrounding the ending, and this version will be part of the base game in Mass Effect Legendary Edition. Hepler feels that "the team got better at some things as we went along." and this definitely includes the dialogue. Mass Effect is all about building rounded characters, and knowing the Krogans have some extra weight just gives the game some more color.
Source: TheGamer