In every book someone mentions that Harry looks like his father...

[vmonte]

No: HPFGUIDX 100970

vmonte here:

I started reading OOTP recently and came across the scene in 12 GP 
where Molly tells Sirius that Harry is not James no matter how much 
he looks like him. It made me start thinking about all the other 
times in the series that wizards/witches have commented on this. I 
began looking through all the books and found that there are multiple 
times where Harry is told that he looks like his father. (In OOTP 
alone it is mentioned multiple times.)  

Why would JKR continuously tell us this? We already know that Harry 
looks like James, so why beat us over the head with it?  Has JKR 
added this bit of info into every book so that we don't forget?  

Throughout the whole series JKR has tricked us with mistaken 
identity.  Harry sees himself in PoA but he thinks it's his father.  
We also have fake Moody, Ron and Harry as Crab and Goyle, etc. 

How would you use this bit of info regarding Harry and James?  I 
think it can only mean that someone will confuse Harry with James. 
But how is this possible since James is dead?  

I think it can only mean that Harry has to time-travel to the past.

vivian