Only two minutes apart, the twins were practically inseparable from birth. As children, their mother would always tell the two girls that When Dabin came out, Da In was clutching onto her sister's hand. The two girls don't really believe that but they do believe that there is a special bond between the two since they were in their womb years. The girls grew up together and did almost everything together from going to the bathroom together because of the scary shadow man, to sharing drinks or food, to getting each other sick because one didn't want to stay home while the other was healthy. Because the girls didn't come from a wealthy or even middle-class family, their parents had to constantly work hard which resulted in little family memories for the girls. Being identical twins, they were very difficult to tell apart for both their parents and others; the only way that they could be told apart as children was because of the different clothing that the two wore. The girls didn't' think so much about being unidentifiable to their parents or those around them because they were twins and they looked as well as acted similarly in some aspects. Although they didn't mean to, this made them to slightly create an almost garden for just the two of them in which they would look out at the people around them through the tinted glass of the garden that separated the twins from everyone else.
As children growing up, the two tended to keep to each other and didn't make many friends because it was just a hassle to constantly correct which twin was which. Around their primary years, Dabin made up a game of guessing the twins because people would always ask who was who so often. The people would almost always guess wrong which slightly irked them paired with the fact that their own parents who created, raised and watched the girls grow up couldn't tell either. Da In didn't mind as much about her parent's being unable to tell her sister and her apart out of love and sympathy since both girls knew that their mother and father gave the girls their all when trying to raise unexpected twins. The girls were still trying their best to be able to be told apart from one another although it still usually didn't help because they often shared everything with the other. The two had a mischevious streak starting from a young age, they began to become pranksters and troublemakers which eventually made havoc a regular whenever the twins were around.
Regarding academics, the two girls were actually quite smart and diligent scholars who maintained grades good enough to get them within the top 5 percentile during their school years. They were suspected quite often of cheating or switching classes since they were unable to be told apart by many people because of the infamous reputation of the imp's pranks during their primary school years but these were false rumors around the rumor mill of high school and the two really created havoc back then just to garner attention and create 'friends' that they kept at a distance. Quite honestly, the girls don't care and would much rather keep quiet and go on with their lives but that there doesn't seem to be any fun to that statement. The girls are careful to not create too much drama in order to not worry their parents because of their carelessness.
It was around middle school when the turning point of their lives came, the people around them were dating quite constantly but the girls being sheltered from this type of life due to their glass wall from the rest of the world caused them to show little interest. Although, due to their looks they were quite popular with the guys around them. During their second year, the gals actually both fell for the same guy who similar to everyone else, was unable to tell the two apart. The girls both confessed to him and later overheard him talking to a friend about them, thinking he was choosing they listened in to hear him jokingly say that he should just date both of them at the same time in order to avoid the confusion of one girl from the other. Those words really affected the two girls who realized that he wasn't the only one with that type of mindset, that people around them were never going to be able to tell one from another nor did they really care enough to possibly try. Because of this, the girls lashed out and decided that if the world was going to be like that, then they would pay it with their own medicine. For the rest of their middle school years, they perfected the art of being identical twins, they wore the same clothing, saim hairstyle and slowly learned how to have the same actions and speech styles. Their classmates and teachers were baffled as to why this came about all of a sudden and confused as to why it seemed to occur so suddenly that the girls were making an extreme effort to keep everyone at a farther distance than before. In a way, this was the rebellion that the two always kept bottled up, no one seemed to be making an effort to tell the two apart to the girls. They were tired of always being mistaken even when they put up a conscious effort to be different, slowly they lost touch with the rest of the people outside of their garden and secluded themselves with thorns.
This act became almost perfect in high school when they stopped the pranking and became quiet, talking to little except each other. As their lives continued to roll, so did their habit of breaking the hearts of boys that showed any interests in them and would try to date them. If someone showed an interest in Da In and asked her out, Dabin would go on the date instead with no notice from the boy that asked. The opposite was done if someone asked Dabin, in a way, this was the twin's way of reaching out and seeing curiously if anyone could actually restore their faith in others which always ended up disappointing the two when it doesn't work. After the first date, during their second date, the girl that originally received the confession would go and tell the boy that they weren't the twin that he confessed to and say that her sister showed no interest in him but she liked him instead. The boys would nearly always reply that he didn't mind to which the girl would call her sister and say "Hey, he said he'll date you instead." before getting up and leaving the guys stunned and insulted.
Over time, the two girls slowly opened up again and began to do things throughout their high school years as to not miss out on the one chance as teenagers. They began to pull pranks again on teachers and classmates alike. To the girls, they themselves were the only ones who truly understood one another and because of this, they shut out anyone else who attempted to become close to them because others weren't even able to get past the identity of one twin from another. During one of the dating games, Dabin got scouted by a representative of JYP to be a model. Getting home, she showed it to Da In who was interested in trying out, but with a more interesting concept. Taking turns to go and take part in whatever they had 'Dabin' go do.