Chitral climate is same for everyone yet Kalash look different then other tribes there.
If anyone of your relative have North Indian look (bihari UP walas types) then its because of North migration in to South. Aryans overtime mixed with indigenous Indus people along with Indians. I think oldest Indus people are Brahui/Baloch types while aryans and Indians are recent migrants in to indus valley.
IVC skeletans have been found and in Sindh/Punjab people were long headed while in Gujarat people were of round heads.
I didnt say anything about my relatives.Any way you point it so I can tell you are wrong.My family members didnt have NI looks.Our community have absolute native features except some eye colour change and skin colour.
Aryans are just a myth created by Brits and Max Muller for enforcing their rights in Subcontinent.