The Dominant Twin

Is it really true that there is always a dominant twin? These guys seem to take on that role and go back and forth week to week. However, with language I noticed that Christian wants to say everything first...well...should I say just talks or tries non stop. When you ask them what something is or a question such as what sound does the pig make...he always jumps the gun! I have been working with trying to let Nicolas speak first... but can't figure out how to teach Christian to wait a second...any suggestions? Nicolas doesn't seem to mind and follows his lead or sometimes just smiles that his brother has answered. I do work with Nicolas if I get alone time. We took a survey recently at dinner that I had with other twin moms and we all found that the child that was born second seems to be more dominant ( Christian). Strange!!! I pretty much have only identified it more recently with language.