I love how The Search had the dumb plot line of "omg what if Ozai isn't actually Zuko's father?!" and actually has Zuko doubting it for a while, when he is literally the spitting image of Ozai.
The writers deliberately created Zuko to make him look like Ozai, who is pretty much the adult version of Zuko without a scar, and who Zuko could have turned out to be just like if things went differently for him.