Since we're talking about Sakura's family, we can also talk about her blood-line.
If we look at Kankuro, for example, one can attribute his cranky personality to the fact that he's ugly, and we only have the Kazekage to blame for that.
I mean, other characters, such a Neji and Gaara also have childhood traumas. We all know that having a big forehead has traumatized Saruka for life. In the very same painful way that it affected the above mentioned characters. So, my question is, is her forehead big enough to justify the trauma she brings from childhood, and explain her behavior?

You be the judge.