Yes colditz and those people are twats. As sunny says, their beliefs about what gender means interferes with a child's natural development. There have been experiments carried out where people have been shown a baby and told its gender (the same baby dressed in different clothes actually) and it is found that the 'girl' is referred to as delicate, beautiful, dainty, fragile. The 'boy' is strong, big, robust. When the same footage of the same baby crying is shown in gender neutral clothing, the 'boy' is angry, cross, acting up. The 'girl' is frightened, lonely, in need of a cuddle. Experiments show that a girl and a boy exhibiting the same behaviour will be talked to in different ways. Boys are told directly 'no' or 'stop' or 'that is wrong'. Girls instead are talked to, their options discussed. They are just a few experiments. I'm not denying hormones and muscle mass and gender difference but socialisation is affecting natural development all the time.
Of course you refer to your own experiences and no doubt you are defensive of the behaviour of your own children. But it's no worse than other gender presumptions from other parents. As I said, I have to listen to the 'oh God at least I know ds won't end up a bitchy, manipulative, hormonal, pink-obsessed, eating disorder-ridden girl'.
I know Dads who will not allow their sons to do ballet because it's gay or for girls. I know Mums of boys who won't let them have a doll, worry when they play with dd and dress up as fairies, make apologetic faces and tell me dh must be disappointed not to have a boy to play football with. DH doesn't care. DD likes rugby as it happens.
And if a child is running towards dd and I can see that that particular child is going to crash into her and I pull her out of the way, I do so because I'm attempting to limit any damage to the pair of them. But if that child happens to be a boy, then the mother looks at me like I'm frightened that a boy is near my girl and is being too robust. No doubt some mothers of girls think that way but just because I have a girl and an isolated incident takes place, like I don't know referring to the two boys outside playing with swords, doesn't mean I am making value judgements about their gender.
I just thiink labelling them SMOGs and saying they are the worst and boys are criticised and penalised more is not fair. Twats are twats. And they don't limit their twattish behaviour to exclude judgements about other people's children.