Why girls can be boyish but boys can't be girlish

For his birthday this year, my 5-year-old son asked for a My Little Pony sweatshirt. He didn't know that it was categorized as girls' clothing, only that, like his beloved Rainbow Dash, it was polychromatic, glittery, winged and perfect.
Source: CNN.com - Health - Category: Consumer Health News Source Type: news
More News: Boys | Girls | Health