Until what age is it acceptable to develop a fashion sense?

well most straight guys wear anything... they don't care how they look. and somehow its mainly the gay guys that are into fashion. not all gay guys are that way and not all straight guys r the opposite. but u shouldn't b too surprised to see straight guys with no fashion sense.. i don't know about the age, shouldn't really matter. like any other interest, u pick it up at random times and keep it up as long as its fun..