Constant harrassment and denigration at a young age
Until you fight back to stop it.
The sad thing is that it isn't only children who pick on ginger people (children will always find someone to pick on because children aren't actually "little adults" despite what their parents think, and they will pick on the minority that is visibly different) it's adults as well.
Every couple of months when walking down the street minding my own business, someone will find it very amusing to very vocally point out the colour of my hair. Whilst I personally think this is a big step up for them intellectually, if you did that to a black person or disabled person you'd be vilified and possibly arrested.
I think people underestimate the effects of fairly constant bullying and demeaning on someone. Each attack taken individually is fairly minor, but as a whole it can leave people with no self-esteem, depression and other lasting issues for many years.
Sadly every few years if you get a group of equally-nonintellectual idiots together, they take it further. Having spent time in hospital because of this, I can no longer agree with the opinion that it is 'a bit of fun', 'larking about' and 'take it like a man'. Red hair is not a choice, unlike piercings, weight and clothes style. It's as genetic as skin colour and sex, and should be afforded the same weight in law.
However I don't think that hair colour is as big an issue with gaining employment as sex and skin colour. It's far more of an issue when it comes to bullying, harrassment and social prejudices, and should be equal in the law in these situations.