I think it's either just her personality or how well she was socialised as a kitten.
We got our Bengal Dexter from a good Breeder and he was the last in the litter. The Breeder reduced the price because he was (and still is a little) very timid. She was very open and honest with us about this.
He hid from us for quite some time even though he made friends with our old Burmese quite quickly. I think also sometimes when you have two cats and one of them is a little timid around humans they can stay a bit like that as they have the company of the other cat and that's enough for them.
My other cat, the Burmese has always been a bit grumpy which is unusual for the Breed. I blame the Breeder though as I noticed when we went to visit she had him outside in a pen and I got the feeling he hadn't been socialised very well.
Our other Burmese (who has sadly passed away with old age now) was totally the opposite and a big cuddly teddy bear. When we got him from another Breeder she opened her living room door and they all came trotting in, every single kitten as confident as the other. They were into everything and adorable! The Breeder's husband also carried them around in his cardigan pocket
.
So I think it can either be just their personality or how they are socialised by the Breeder.