Why am I so bias towards my team[s]?

everybody has a bias, admiting it is actually a very important step. Because after someone admits it they can take your views in context. I think it is important for news outlets to also point out their bias, so you can keep their views in perspective, for instance the Economist is very open about its European Liberal bias(which strangely has no counterpart in America lol, but I identify most with:/), and I find it helpful to keep that in mind while reading it.