@BertieBotts it is very interesting, but unfortunately we used to get a lot of customers who would come in, kick off about it, wouldnt listen to the reasoning, and would actually refuse to believe me that we only had one bay and one table extra for girls, even though it probably took a third more money! Those same customers would leave with a pair of mid blue denim jeans, a checked shirt, and, if they were feeling daring, a t-shirt to layer it with for their boy - revolutionary 😁
For girls, people will tend to buy as an outfit, not mix and match, and people will buy as gifts, so girls have more clothes. Boys will also have more characters/ slogans, while parents of girls want a look, often to reflect their own- cool, boho, rock, cute, often means more clothes. However much people say they're not bothered, we could predict the bestselling collections as soon as they came through the door!
Honestly, if you want something different, do take a look at Zara, and if possible go into a store in a smaller area to look at outfit ideas- the company does really well at promoting new looks and fashion for both sexes, but the stores in shopping centres have such a high turnover they can't always make it look fab. The Leeds briggate store has some fantastic merchandisers working there. I miss merchandising kids outfits! And I do find the marketing science fascinating.