I've had similar with my own DD & she has had problems with taunting over it which started very young at about 6yrs - I have wondered about a Thyroid problem as its rife in my family, but again the GP said that its all normal & after a few years, I think it probably is amongst the darker haired/eyed DCs.
The DCs taunting my DD were all very fair & I noticed looking around the darker DCs that a lot are very similar to my DD, it wasn't that my DD was different, it was just something that those DCs doing the taunting could pick on DD for IYSWIM - kids being kids, there will always be something they can single another out for, no matter how silly it is, so you can't protect her from taunting, personally I've found it works far better to teach my DD that its all normal & just the way some people are, get used to it & get used to taking no notice because it"s the quickest way to get them off your back & winds them up far more than arguing back
That said, I found out about it all because DD cut herself trying to shave her own leg without my knowing - using her Dads razor :( - she was so upset that I also looked into how was best to deal with it, as she was already now very self conscious over her legs & even arms :( - I found out that it's not at all uncommon, though usually kicks in a bit older & I bought my DD some Silky Mits they are safe for her to use herself, which I found helps her to feel in control & less embarrassed, they also just thin the hair out & make it less noticeable, so not so drastic from a Mum point of view.
DD is now nearly 10 & she did upgrade to getting a lady shave for a birthday gift a couple of years ago, which uses depending on what she's feeling like or wearing, she can go through months of not caring & at other times she will, but thankfully she insists she does it for herself, she is very aware of clothes etc so I believe her :)
If your DD isn't bothered yet, then I personally would just leave it, but keep a close eye on her & the dynamics with her friends, girls certainly keep you on their toes with their friendships, so it will most often be pretty easy to spot who the taunting culprits are likely to be
- & if they are fair haired/skin or other less hairy skin types, then your DDs legs will be different to theirs, so it may become an issue early as it did for my own DD & thats probably the best time to address it with DD.
Also you might want to think about a moral story book, that empowers her a bit - I think my DD liked Rainbow Fish at the time, but theres lots of other I'm sure - if not just make her one up :)