Why are the flags of northern European countries the same?

Please help us fund our second channel that reveals the secrets around us!the second channel, which reveals the secrets around us!thank you
https://www.youtube.com/channel/UCf5z... Hello friends. Have you ever paid attention to the flags of the 5 Nordic countries: Denmark, Finland, Iceland, Norway and Sweden? They all have a similar texture and shape, only the color is slightly different. So what should they do with each other? The answer is yes. The Nordic region is home to over three-quarters of Scandinavian people, with a common ancestor being Old Norse. They share the same history and culture and can understand each other's language.
the flags of northern european countries are the same? why are the flags ______ of the same northern European countries?
Hello, friends. Of the five Nordic nations—Denmark, Finland, Iceland, Norway, and Sweden—have you ever noticed them? They differ slightly in color, but they are all similar in feel and shape. What do they therefore have in common? Yes, that is the answer. More than 75 percent of Scandinavian people live in the Nordic region , and they have Old Norse ancestors .
They are able to understand each other's languages ​​and share the same historical and cultural background. There were movements in the 19th century that demanded Scandinavian unification. Combine Sweden, Denmark, and Norway into a single nation. But it