Over the years of being an #18 fan, I've heard a lot of rumors. Some of them turned out to be true, but for the most part, the things I heard and some of the things I used to believe were completely false. Who starts these rumors, I don't know, but this section is here to clear the fog.
Myth: #18 is an android.
Answer: Indisputably false.
Explanation: Despite Viz and FUNimation labels, #18 is part human, making her a cyborg. This misconception is covered most extensively in the Cyborg or Android section.
Rumor: #18 used to be a cyborg and then turned into an android
Answer: Indisputably false.
Explanation: It's rumored that #18 used to be human, but then received so many cybernetic implants from Dr. Gero that she turned into an android. I would love just to say that this rumor is false for obvious reasons and be done with it...but people don't make things that easy for me. Why anyone would believe (and sometimes argue in defense of) this rumor at all is a mystery to me, especially when any person with common sense knows that it is impossible for a cyborg to turn into an android. You see, an android is essentially a robot with a humanoid form. A cyborg is an enhanced human (living being, if you prefer).
Now that you know this, you must ask yourself: is it possible for a human to turn into a robot? No, it isn't, no matter how many cybernetic enhancements or replacements you receive. That's all there is to it. If you're still not convinced, though, check out the Cyborg or Android section.
Myth: #18 was turned into a human by Shen Long.
Answer: False.
Explanation: It is true that Krillin asked the dragon to make #18 and her brother fully human again, but such a wish was beyond the dragon's power. Instead, the dragon removed the bombs inplanted in them.
Myth: #18 has no emotions.
Answer: False.
Explanation: This rumor can be blamed on the misconception that she is an android - you know, she's an emotionless robot or something. But Eighteen is part human. In fact, she was a teenager when she was made a cyborg, and we all know teenagers aren't much more than a sack of hormones and emotions most of the time. If #18 truly was emotionless, Toriyama would have always drawn her with an expressionless face, which he doesn't. There are more panels in the manga than I can count where she's seen smirking, annoyed, shocked, or just enjoying being herself. Granted, her pleased expression is sort of straight-faced, but there's a haughty, tough-girl feel to it. And true, she doesn't interact much with the Z gang in any great depth, but that's more than likely because they're just not people she relates to - not because she is "emotionless".
Myth: #18 has endless energy.
Answer: True.
Explanation: Dr. Gero implanted special generators inside #17 and #18 that give them endless energy. In #18's fight with Vegeta, Piccolo notes that while Vegeta is doing well against her, he is getting tired and she is not. When Piccolo and #17 fight, #17 taunts Piccolo by saying that he won't become fatigued and run out of energy like Piccolo will. These are the only two jinzouningen Gero made with the eternal energy generators.
Myth: #18 feels no pain.
Answer: False.
Explanation: While #18 does have the superhuman abilities of flying and endless energy, never is it stated that she can't feel pain. The blank expression she carries on her face during her fight with Vegeta might be to blame for this myth, but one has to remember that she was stronger than him at the time, and thus not affected by his attacks. During nearly all of her other fights, however, she grunts, grits her teeth, and draws her brow together, signifying that she feels the force of the blows being dealt upon her.
Myth: #17 and #18 are the same power level.
Answer: False.
Explanation: #17 is the stronger of the two twins. I believe someone mentions this briefly in the show, but I'm not sure. This information is stated, plain and simple, in the Android A B C chart.
Myth: #18 is the older twin.
Answer: True.
Explanation: In the Japanese manga, #18 calls #17 her brother. The word she uses for "brother" consists of certain kanji that signify he is the younger brother. This is explained in length over at K&18: Family Photos, where it has a special page all it's own.
Rumor: #17 and #18 will never age.
Answer: ???.
Explanation: Family Photos says that because of their generators, they have unlimited power and do not visibly age. I can't verify that information, but I have to agree nontheless. Simply because they are cyborgs and have unlimited energy does not mean they will not need maintenance and will not age. This rumor is arguably false.
Rumor: #18 doesn't love Krillin.
Answer: False.
Explanation: This rumor is probably based off that damn emotionless myth. We know the emotionless myth is false, though, making this one false as well. True, we see #18 acting a bit unkindly to Krillin sometimes , but out of all the couples in Dragonball Z, she is arguably the most affectionate. She's pictured together with her family more often than any other couple. We even see her typical unamused expression break for a smile when Krillin decides to provoke it. If you watch the third Brolly movie and practically any episode of the 23rd Tenkaichi Budokai, you'll see plenty of what I'm talking about. Honestly, if #18 didn't love Krillin, I don't think she would've bothered to find him after the Cell saga and bear his child.
Rumor: #18 loves to shop.
Answer: Arguably true.
Explanation: Can't deny that! The fact there are multiple scenes devoted to #18 shopping is enough evidence for me. She likes to look good, dammit. I personally think it's cute to see her shopping, but find it irksome when people use that as an excuse to say #18 is money hungry. They cite her throwing the fight to Mr. Satan for some prize money as proof, but if she was money hungry, why did she marry Krillin, who is still living with his master? #18 is just a wise woman, I say.
Rumor: If #18 continued to train and didn't settle down, she might be as strong as Vegeta or Goku.
Answer: False.
Explanation: Someone asked me this once, and I thought about it for a moment before deciding it was not possible. #18 is essentially a human, and (without cybernetics) she could conceivably only grow as powerful as the strongest humans (Krillin, Tien), who are far below the saiyans in power. So yeah, she could be that strong on her own, but one has to remember that we don't know if #18 was a warrior like the other humans in the Z gang. We know that she was a "notorious delinquent" before Gero turned her into a cyborg, and I don't think being a a famous gangster involved the strict training and manipulation of one's ki. As far as I'm concerned, #18 was an ordinary teenage girl before she became a cyborg, and probably one that was barely as strong as Videl is.
Let's throw those cybernetics into the mix now. #18 is a badass. When she first arrives, she easily holds her own against Vegeta, the most powerful saiyan at the time. We know she has an endless energy generator and has had her body enhanced to work with it. However, we also know that her ki cannot be sensed by the Z warriors, who are extremely sensitive to it, the life force in every being. Perhaps having those cybernetics dulls that life force, or even strips it away from her. If that's the case, then we can assume that her power can only grow as much as her cybernetics can allow.
So what causes her power level to rise as the DBZ series progresses? Well, we can either assume that her cybernetic limits had not been reached, thus allowing her growth, or that she found her living ki amidst the mass of artificiality and helped it grow (with some training from her husband, perhaps). Hell, her power level increase could even be due to both of those possibilities. Could she become as strong as super saiyan 3 Goku, though? Unless her cybernetics were replaced with some amazing new upgrades, hell no.
Rumor: #18 is a bitch.
Answer: False.
Explanation: Eighteen is a confident woman. Dudes often confuse confidence in a female with being a bitch. She's not too sociable, yes, and she gets annoyed by the Z gang from time to time, but she's not a spiteful, overbearing person. Maybe to Krillin she's a little harsh sometimes, but that's about it. #18 doesn't get all up in people's business, threatning them with blackmail like some females in the show, that's for sure...
Rumor: Videl can kick #18's ass.
Answer: False.
Explanation: I don't know who came up with this idea that Videl was tougher than #18. I can't believe it's true and till someone shows me official power levels from a Daizenshuu or something, I'm going to say it isn't true. How can Videl, a human, be tougher than #18, who is stronger than the strongest humans? That's all there is to it.