Despite all the controversy around it, I myself would like to still encourage you to introduce your children to clothing that is not aimed at their sex. Give them a choice of what they can wear. And if they're too young to express their interests, try and mix it up like I do and have a few things from the 'girls' section and a few from the 'boys' section.
People that I've spoken to say that this is harmful to the children, that we are basically handing them to society to be shunned and bullied. But I do not think this is the case. Children will bully each other and then decide on the reason for it. As soon as attention is drawn to you in school, the bullies will join to make fun of it. In school I was bullied for lots of things, for not having a boyfriend, for being short, for being nerdy, for not having had my period yet. For being related to my brother. These reasons are all ridiculous, as ridiculous as it is to bully a child for having a dinosaur lunch box.
Don't you think that it's more important to teach your children to be themselves and to own their identity (thus giving them confidence and self esteem) than teaching them that other people are in control of you? Control of your choices? That you CAN'T do that or you CAN'T do this? Telling parents to deny their children the choice of wearing and playing with what they like is telling them 'it's okay' to treat people this way. To exclude them and give them different rules to each other depending on trivial things. Would you do this for race or disability? So why do it for sex?
We all have difficulty in finding who we are when we're growing up. Our visions of ourselves are clouded by how other people see us and treat us. It usually isn't until adulthood that we finally find who we are. And then we continue to discover and change. But one thing that I found when I was soul-searching is that I had all these little quirks. Things that I liked, and for no reason at all. I like ribbons (though I had fought against this because I was taught that bows are 'feminine' and I do not relate to being female - so I didn't allow myself to appreciate this interest because it was 'girly'). I also like things with legs, and the idea of suspending things from the ceiling. I like the colours orange and grey the most. When I grew up, I realised that these things that I liked for no reason were like a peephole into who I really was, and it's only once I decided to not give a damn about if it was girly or boyish or whatever, that I could embrace who I was. And those personality traits finally became me. And then I started to like 'me' because I wear bows and cute skirts and ties and everything I own is orange and I thought it was funny when the red die in my towels made all the muslins pink and I tell cheesy jokes and wear a fluffy tail and don't care what anybody else has to say. Because I like all those things.
So despite what people may say, I think it is so important to encourage our children to embrace the things that they enjoy, love and care about. Not so as to push them into growing up quickly, but so they can have as easy a time as possible when it comes to discovering who they actually are amongst all the 'should be's.