Okay this part won't contain spoilers.This is the information we will give you for this part.

  I often hear from many people, especially those who ship the popular pairing Ereri, say that Eremika is a bad ship because it is Incest. Why do they think this? For one it's because Eren and Mikasa grew up together, two Mikasa acts like a mother to Eren and only sees him as a brother.

Now after thinking about this for a long time, I have come to know that they aren't accurate reasons. For one, Eren and Mikasa have no family relation in the slightest, there haven't been hints in the show or the still continuing manga that there is even a slight possibility that Eren and Mikasa are related. Mikasa wasn't adopted by Grisha, he simply took her in to take care of instead of sending her to an orphanage or leaving her be. If you see that while reading wiki or reading a translated version of the manga or show, then the translation is wrong.

Now the main reason saying they grew up together means they are incest doesn't count because almost more than half the people who get together today grow up together, or even saw teach other when they were born. Not only that but Mikasa was with the Jeager house hold for only a year before the colossal Titan appeared. For another example, if just because someone grew up together makes them sister and brother, means that my sister and her husband are incest because they knew each other for years.(my friends sister not mine)

It doesn't make sense for it happens currently all the time. Children from kindergarden grow up together and get married when they are age appropriate, some people take people in there homes to stay and they live together for years, so by the logic of why Eremika is incest, practically makes almost every couple incest around the world. There is also someone who is a friend in my family who has been with us for years, and I guess because if my brother, or someone in my family got into a romantic relationship with one of them and they grew up together, that means they would be incest.

Another thing is that there are quite a few anime's that have incest couples and a lot people actually like them(I'm not one of them), and yet when it comes to Eremika it seems to be wrong and terrible. Same thing coming from the Ereri shippers (no offense intended, I just get this all from them since that is the famous ship here) they dislike Eremika cause they say it's incest and yet ship a pedophile pairing. I'm sorry to say this and I don't want to sound rude, but if you think Eremika is incest and yet like Ereri and incest couples from other animes, you are being completely hypocritical. For both pedophile and incest are equally bad.

This is mainly just a theory, but when Mikasa and Eren met, their parents were trying to get them to meet up. In those past times it was not uncommon to have arranged marriages. Eren and Mikasa never knew each other before and never had a connection in the past with each other's families, so it's not impossible to believe that Grisha was trying to get Eren and Mikasa together. But yeah again this is just a  theory.

I know that some people don't ship it because they think it's incest, but because they believe that Mikasa acts like a mother to Eren and he only sees her in a motherly way. But isn't there that saying that when a woman is in love she acts like a mother and when a man is in love they act like a child? I know this is true from close examination of my mother, father, and others in family that are married. It couldn't be that she really does see him as a son or brother for Mikasa has blushed over people including Levi calling Eren her boyfriend.

Mikasa has called Eren family and never brother, she also seemed unsure when one time when someone called Eren her boyfriend. Saying "he's...he's my...." As you can see from watching those parts, she is completely unsure how she feels about Eren.

Now Eren has never called her his sister, and even though he dislikes how she frets over him, he still cares and recently is being nicer to her than before. (Spoiler alert) Eren and Mikasa almost kissed in the manga, Mikasa being the one to initiate the move, blushing and thanking Eren for showing her how to live and the only reason Eren moved away was because if he didn't act, then everyone would have died then and there. But while he was saving them, he gave passionate and deep words to Mikasa saying "I'll wrap that scarf around you as many times as I need to-" and "From now on we'll keep being together."

What could that mean? Eren is not one to show his deep feelings so publicly, and during that time he was even in one of his slight rages. Could what he be saying hinting to possibly him liking her? Eren has also as I said been nicer to her, not complaining when she fretted over his health and it all happened right after he said those words and Mikasa tried to kiss him.

Even though Mikasa had been brought in as a child, homeless and an orphan, she still goes by the name Mikasa Ackerman, not Mikasa Jeager. If it was possible that the writer didn't want any possible chance of them being together, wouldn't he have made them brother and sister from the beginning?

Mikasa and Eren have no proof of being incest if they get into a relationship, and saying that they are is a very weak argument. This is all I have to say for now, this is mainly just clearing up Eremika and stop the hate it doesn't deserve.

Thank you for reading and again please take no offense into this, I only take joy in reviewing and understanding opinions. It's okay if you don't ship Eremika, but hopefully this will change your view on the shippers who adore this pairing, and stop the silly 'fact' that they are siblings/incestral but critisize eremika if you don't know the reasons you ship it.

PS: Please tell me if I missed anything

EDIT
 But as of the moment, time is not very friendly, so I'll just put a couple things down that I've dicovered over the years.

Now, if the wikipedia says that Eren and Mikasa are adopted children, you cannot go believing it just because it says so there. Anyone can edit the content and wiki is NOT always the best source to get your information. Thanks to Japanese translators and readers from tumblr that I follow, it is confirmed from the attack on titan information book, that Mikasa was only taken in, not adopted. And if you are a manga reader, and you're cought up with chapter 89 at least, you'll know there is a reason Grisha took her in.

In the manga and anime, Mikasa and Eren never refer to each other as brother or sister. Neither does Mikasa, call Grisha and Carla mom and dad-or otousan(father in Japanese) or okaasan(mother in Japanese). Also in the recent new season of AoT, Mikasa refered to Eren's parents as "his" and not "ours". In Japan, unlike english, communication alone is enough to tell the relationship or what status said other character has with the other character(s). You can say, "well, I tell my sibling "your mom" is calling you" but I'm afraid that's not how it works in Japanese. English and Japanese are different. You can rewatch and reread the shingeki no kyojin show/manga, and not once will they refer to each other as being of relation.

Mikasa says "he is family" however, family has various meanings to it other than someone you're actually related to. Like having a friend you could call family, or a husband or someone you like, they can be family to you. It's not strictly in terms of related people. And of course, as we all know, Mikasa still has her last name. If an adoption occured, her Japanese information would say (adopted by the Jaeger's) and her surname would have changed. However, such a thing has never occured. 

COMMMMMEEEEEENNNNNTTT AND SAY PLEASE IF IT IS GOOD INFORMATION !!!!!!