“Gill also reminds Chan, “We have used a traditional mean–variance approach to optimize your current portfolio allocation, but this will not be appropriate for a portfolio that includes substantial allocations to alternative investments. Returns to traditional asset classes are normally distributed, whereas returns to alternative investments tend to exhibit non-normality. ”请老师解释以下，为什么这句话是不对的？alternative的return不就是non-normal的么？它应该是left-tail才对的呀？
