It isn't just human though. As a general rule, male creatures tend to be more aggresive than female creatures because of the greater amount of testosterone. A large part of creature behaviour is chemical, and that affects behavioural tendencies.
Dragons - either sex is good. I think the most important thing is to define Dragon culture, and then allow for sexual behavioural variance. That way, your dragons will act like dragons, but gender will still affect individual behavioural patterns.
Hope this helps <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />