[ CC ] [ PI ] Every person in the world is born with a twin that is separated from them at birth for the entirety of their life by the government . One day you meet your twin and find out why all the twins are kept separated .

This is a great story, I really enjoyed reading it. Your writing is very solid and there's not a great deal to fault with it, but since you asked for criticism I've gone through and picked out anything that I feel did n't work as well as it could have. None of these are deal breakers, but if you're looking to apply the next level of polish or want a few things to take away for the next story, then hopefully this'll give you somewhere to start. 
 
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 > My craving for distance was ended when a clap of thunder shook me and the canopy above me. My knees buckled and I crumpled to the damp blanket of leaves covering the ground. I let myself fall back, rubbing my hands over my face, preparing to make the journey back, hopefully at a quicker pace to outrun the sudden storm conditions. 
 
 This paragraph feels a bit weak in a number of ways. 
 
 In the first sentence we're talking about a clap of thunder strong enough to break the narrator's resolve *and* make her fall to the ground to boot, but the way it's described right now feels very unengaging.'My craving for distance was ended' is not just passive voice ( which is usually worth avoiding since it's less engaging ), but it's also a very bland verb -'ended' really does n't evoke anything in the reader, it's just a statement of fact. Re-write this sentence in the active voice ( A clap of thunder VERBed my craving for distance, shaking the canopy above me ) and pick a more powerful verb like'broke','cut short','wiped away', and you've got yourself something much more powerful. 
 
 The final sentence suffers from a similar problem. It's not passive this time, but it's still taking what should be a fairly big deal ( the narrator's decision that storm conditions are imminent and she needs to turn back ) and telling it in a way that just does n't engage the reader or convey any of the emotions that are surely going to be involved in that decision. In fact, we do n't even see the decision - we just go from the narrator falling over, to her preparing to head home. On top of that, I think the sentence probably runs on too long - you've got the action ( falling back ), another action ( rubbing face ), a thought process ( preparing to return ), and an additional clause ( hopefully quicker because storms ), all in one sentence. That's a lot to process! 
 
 I'd suggest splitting this up into something like: 
 
'I let myself fall back, rubbing my hands over my face. Rain water was beginning to pour from the canopy, and dark clouds churned in the skies above. * ( Basically some sentence to establish her recognition of the worsening storm - show do n't tell ) *. It was time to turn back. With a quicker pace, I should be able to outrun the storm. * ( The narrator's decision and thought process. Elaborate on this a bit more if you like, e.g. to talk about her fear of getting trapped if the storm worsened - is she in a particularly bad place to get caught out )? * 
 
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 > “ Do you want- do you want to come with me? ” I stammered, turning my back on the familiar stranger when she nodded a third time. 
 
 The ordering here is a bit awkward. The main culprit is that the part of the sentence that tells the reader what order things are happening in ('when she nodded a third time' ) does n't come until the end. This structure works fine for instructions ( e.g. `` make sure you answer the door when he knocks'' ), but I do n't think it's a very good way of reporting live action since it tends to break immersion - the reader will envisage the action happening, but then you tell them that the action did n't happen until AFTER something else which forces them to go back and reassess. 
 
 What makes this one especially awkward is that it's happening in the same sentence as the narrator's speech. The ``... I stammered, turning...'' sentence structure usually describes things happening simultaneously, so it misleads the reader to think she's turning as she talks. Except as we find out afterwards, she's actually turning as a result of her twin nodding, which in turn is a result of her asking the question. 
 
 I suggest breaking up the sentence so you separate the speech from the action, and switching up the structure of the second half so it's clear that she's turning as a result of the nod. 
 
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 > I planned on taking her to my apartment and figuring out where she came from and deriving a plan to get her back. 
 
 Just a small one, but I think the structure of this ( X and Y and Z ) could be better. If you were explaining the plan to someone, how would you explain it? 
 
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 In the dialogue between the narrator and the cop, there are a few snippets that just do n't sound very natural. For example: 
 
 > Well, not as a separate human. 
 
 This one's forgivable since she's babbling, but it feels like an odd way of saying it. 
 
 > Which I am glad was so easily accomplished thus far, 
 
 I guess the cop could just enjoy being a bit pompous from time to time, but this sounds too formal for speech. Try saying it out loud - if it feels laborious and/or you ca n't imagine actually saying it to someone, chances are people would n't use it in real life and it'll read weird as a result. `` I'm glad you've been so understanding'' or `` Which I'm glad you've been so willing to give'' seem like they would work better. 
 
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 > It grew cloudier as we drove, only a crack of sky blue here and there, but no threat of rain or storms. 
 
 Should that be'blue sky'? 
 
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 > We pulled up outside a bland brick building with no determining factors other than a sign at the end of the drive that read “ INVESTIGATIVE HEADQUARTERS. ” 
 
 This feels like another pretty long sentence - I'd probably put a full stop after'building' and then describe its lack of features / the sign in a separate sentence. 
 
 While I know what you intend with it, I'm not sure'no determining factors' ( i.e. no factors that have decisive effect on the outcome ) is the right phase here. Do you mean'no distinguishing features'? 
 
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 > The officer punched in a code to unlock the second one and took my twin inside. When he emerged, he moved to the first room and punched in another code and led me inside. 
 
 Since you've got another sentence between describing the rooms and this one, it's probably worth specifying'the second room' instead of the generic'second one'. 
 
 Your second sentence here is another example of'X and Y and Z' - it's a slightly awkward sentence structure and I'd avoid it. To be honest, you probably do n't need to repeat the description of him punching in a code etc. anyway - the reader should be able to infer it quite easily. Just say that'He emerged after a few moments, and lead me into the room beside hers.' ( Or something like that ). 
 
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 > He looked at me under his hooded eyes with a gentle look. 
 
 This feels odd with the repeat of'look' ( also, he looked *under* how eyes? Surely the eyes do the looking ). Avoiding too many adverbs is a good idea, but'gentle look' here is really just an advert in disguise, as the cost of making your sentence sound weird!'He looked as me gently with his hooded eyes' does the job better. If you want to avoid the adverb, maybe try something like: 
 
'He looked at me with his hooded eyes, but his face had softened.'' 
 
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 > I had never been in handcuffs before, never even got a ticket, now here I was in an interrogation room, and an inkling that I was about to learn something. 
 
 Long sentece again with too many clauses - break it up! I'm pretty sure there are also some words missing from the last clause.'and I had an inkling' maybe? 
 
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 > I wrung my hands in silence for what I imagined was ten minutes, but in reality, I had no idea how long I had been sitting there when the knob turned and a professionally-dressed women entered the room with a manila folder in hand. 
 
 Another long multi-clause sentence, but this one feels especially odd since it's mixing an action that happened over an extended period ( the hand-wringing ) with something that happens later at a specific time ( the woman arriving ). It's up to you how exactly you go about it, but I feel like you need to break this one up a little bit, e.g.: 
 
'I wrung my hands in silence for what I imagined was ten minutes, but in reality I had no idea how long I had been sitting there when the knob finally turned. The woman who entered was professionally pressed, with a manila folder in hand.' 
 
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 > The scratch of the pen was melodic with my heartbeat. I pressed my right thumb into the pulse of my left wrist. 
 
 This feels... odd. The first sentence seems overly flowery without quite hitting the mark ( I see what you're going for but it sounds a bit weird and out of place ), while the second one is incredibly specific and literal. The first sentence could probably use some work, the second just needs to lose the reference to a specific thumb and wrist ( just say'I pressed my thumb into my wrist, feeling the pulse' or something like that ). 
 
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 > “ The simplest way to put it is, the creation essentially copied everyone... 
 
 What creation? The creation of our universe, or something that the scientists did which created the effect? I feel like this needs to be more specific. 
 
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 > Inside, there was a room formed from four double-pane windows in the center, with a slim walkway around the exterior, with a folding chair every couple of feet. 
 
 Repetition of'X, with a Y' feels a bit awkward. Change the first one to'windows in the center and a slim walkway around the exterior' and I think it'd flow better. 
 
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 > almost like the sound rain on the roof of a car. 
 
 Word missing here! 
 
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 > I pushed past my seven-mile mark. I wanted to see how far I could go. 
 
 I think it'd help if you did something to indicate scene changes like this. A horizontal like maybe ( since reddit automatically parses the'three stars' into that )? I'd also put a scene break earlier, when they arrived at the HQ.
