Not long ago I went through four seasons of New Girl which is lead by Zooey Deschanel and now I'm in the middle of first season of Bones which is lead by her sister Emily Deschanel. One can really see the likeness but their looks have different type of character stereotype in my opinion.
For example, think Emily Deschanel as Jessica Day (Zooey's character in New Girl) and you would probably have a hard time seeing her in those girly outfits playing a quirky, singing teacher. Same goes the other way around, think Zooey Deschanel as Dr Temperance Brennan (Emily's character in Bones) and you would have the same difficulty because her look doesn't give the same vibe of seriousness because of her hair and big eyes.
Now, I am well aware that I am going by looks alone since personality is much harder to peg down on actresses I've never met and thus know nothing about. Bear with me!
As I was watching Bones I came to a realisation. Zooey wouldn't fit as Dr Brennan because look wise and energy vibes (at least from the movies/series I've seen with her) it doesn't fit but she would fit as Angela Montenegro, the best friend of Dr Brennan. Angela has the vibe and looks that would fit Zooey.
So I started to think who Emily could possibly be in New Girl and came to the conclusion that she could actually be someone who dates Nick Miller since he's actually been with the more serious looking types before. She could also be a co-worker of Schmidt.
This whole blog post is just late night thoughts so don't take them too seriously, but I find it interesting how looks is so important with characters no matter if it's on TV/cinema or in a book. For example, who would take Pippi Longstocking seriously if she would defend someone in court? You can put a nice pants suit on her but she's still a freckled girl with braids sticking straight out of her head.
Think like this, would you feel the characters still fitted if you switched which actor plays which character on Bones if you switched David Boreanaz (Booth) with Eric Millegan (Zack Addy)? If you have seen Bones you probably say no. Eric Millegan wouldn't fit as a serious FBI agent who is a former sniper and David Boreanaz wouldn't fit as an awkward Ph.D student with high IQ. When it comes to characters it's more than traits and acting, it's also equally important how they look so we will feel they are believable as the character.
That is also why it's so important that we stop with the white washing of movies, but that's a whole other subject for another day.