You can only change your height and/or gender if you have the Science Super Booster pack, and even then only at Cosmetic Surgeons, not normal tailors.
Thanks so much TK, i do have the Science pack and that must've been when i did it last time, i simply didn't remember going to the cosmetic surgeon to do it.
I appreciate the informed and quick response.
Yep, height and gender are the two attributes that can only be changed at the Cosmetic Surgeon. Technically because they are both on the first screen in which you select model and height. I suspect there may be some implementation reason the height slider couldn't be moved to the same place as the other sliders, but it may just be it was left that way to make a little money. (And make the feature more useful to more players than just if it was to change gender alone)
In fact, I was really glad when they implemented the Cosmetic Surgeons, because I had a couple of characters that I wanted to make their legs shorter as they got bigger and more muscular. But adjusting the leg length slider made the character SHORTER, so I needed the height slider to compensate for the increase and make them taller again.
Trying to explain it in terms of the game universe I have a little more trouble with. 
These tailors can increase a person's muscles and breast size, lengthen their legs and even change the color of their skin, but they can't make them taller? For that you need a specialist who is also able to change your gender or make you an overmuscled hulk? How is that related?
RWZ is normally where I go. Nice light you can stand under and also able to adjust your sex and size if you wish.
Hi all,
a simple question really. I've tried to alter the size of one of my toons at the tailor but i can't find the height scaler. I know I've done it before because one of my older toons has two different costume slots, one where she is 4 foot and one where she is 7 foot. Also you used to be able to alter your gender on different costume slots... has this changed and if so, any reason why?
cheers