If you go to any Highland Games, you'll see that 95% of Highland dancers (maybe more) are girls (and I mean girls, not women). 6-16 sort of age range. So that's why I assumed female.

Male dancers wear both dress and dark tartans if they compete as dancers, but most wear 11-13 oz tartan for exactly the same reason - too heavy and hot to leap around in a 16 oz kilt (and the weight of the back of the kilt flying can throw off a spin).