Yin yang twins

Ok, so I have a question for all you twin moms out there? Do twins always end up to being the opposite of each other? 

Since my boys have been babies I have joked with people that I have the blessing and the curse of comparing them at everything they do. Mainly because there are two of them doing the same thing at the same time.

As my boys grow older, I am watching them day by day split personalities from each other right in front of my eyes. I am seeing them literally become the opposite of each other. Where one is dominant the other might not be. Where one child struggles the other may excel. Where one chooses art the other feels the need to name himself the sports guy. 

They have always been close. Up until about 5 years old, they have always been pretty similar. They haven't been too competitive(I tried really hard to dodge that bullet and am still waiting for it I rear it's ugly head. I do have boys after all). So far, they really have genuine concern for one another. 

But now I see them everyday become the ying yang of each other. I am not sure how I feel about that. I am not sure why it is bugging me. 

I realize they are two separate people and I do not need them to be the same. I do not need them to be interested in the same thing but I have noticed a pattern lately that is unsettling.

I am seeing if one kid excels at something it kind of counts the other kid out. For example: if one guy shoots the ball really well, I see the other guy slink as if to say "well I guess he is the one that will be better at basketball". I watch them mentally assign themselves or their brother different roles and then not also trying that role out for themselves. Almost as if they see themselves as one unit. I wonder if anyone else out there has noticed this too? 

So help me out, are your twins the opposite of each other? Do you think it is like a marriage where you kind of just pick up where your spouse leaves off? At what age did you notice them splitting up?  How do you or did handle this? What happens next? Feel free to leave your comments below.