You are flawed, and so am I. We carry our defects of character into fatherhood.
But there's hope.
Before we get kids, it's easier to ignore some of these flaws. People who care about us might give us feedback, but it's nothing compared to the feedback from a child.
Kids mirror our repeated behaviors.
Be generous around your son, and you will witness him being generous in turn. Show repeated impatience and expect your daughter to do it, too.
Direct, fast, raw feedback. Ruthless. Impossible to ignore.
If a friend says, "You shouldn't have answered him that way; it was rude," you can brush it off. You can tell yourself that you had good reasons to do it or that it's just who you are. Take it or leave it!
But when your daughter shushes her little brother with a strong "SHHHHHHH!!!!!!" and an irritated mimic on her face... that pierces your heart. She saw you do that. You have no excuse.
Whether we like what our child mirrors us or not, we are always given an opportunity.
If it's a negative character trait, we can work to correct it. We can resolve to pay attention and stop shushing our kids that way, even though we've already told them thrice to calm down.
And if we recognize a positive character trait they have inherited from us, we should take it as a proper encouragement to do more of it. Positive reinforcement!
Every time your kid pulls the veil, you get a chance to become a better dad.