Twins vs. Singletons

I'm finding out that twins are not the same as having a singleton.  I've noticed a lot more of their personalities at an earlier age, and the emotions that they have and show are a lot more noticeable.  I'm not sure how much of that is a twin thing, but I really don't remember The Girlchick having such intense emotions at this age.  For example - Thing 1 gets really angry, and it is very obvious that he is mad, not frustrated or just upset, but very mad.  You can tell by the tone of his voice and his actions.  He will tense up and growl and kick his legs out really hard, not like a tantrum, it will only last a few seconds and then he is done.  But I've never seen a baby angry, it's interesting.  It seems that their emotions are in general more intense.  Again, I'm not sure if it is a twin thing or the fact that there are 2 babies around all the time.  I need to look into this more.  But it is a lot of fun to watch their interactions with us and each other.