But before you even tell them why they have to wear tights and a dancebelt, get their waist measurements and then purchase a black or tan dancebelt for each boy and black tights or a unitard. Tell the local dance/ballet store their measurements and if you plan to get unitards for them other measurements are needed such as torso, chest, etc. Because the boys are 12 and 14, I would not make them go with you the first time to a dance/ballet store but I would also not tell them you're buying them the clothing either. Why? Because like most boys who have an interest in ballet they know they're going to have to wear tights eventually.
So when they come home from school one day, have their tights and dancebelts laid out on a chair or bed in the privacy of their rooms. Don't even mention what is waiting for them and when they do see the gear and if they balk, tell them they must try on the dancebelt (and yes, tell them how it must be worn) and tights. Be firm with them about this. Once they have put on their tights/unitard, tell them you want to see how they look. They may feel awkward wearing the dancebelt and tights but for the first time they are wearing them make them wear it for a couple of hours in the house to get used to the feel and fit. If they're wearing tights they should wear a white T-shirt tucked in under their dancebelt or tights. Because their dance instructor(s) will want to see snug fitting tights, make sure their tights and dancebelts are pulled up very snug.
Of course this new experience for any male, especially teenagers, wearing a dancebelt and tights may involuntary cause an erection, especially when putting on the dancebelt, that's why it's important they wear the dancebelts and tights around the house to get used to the fit/feel. Most males, even when practicing ballet, do sometimes have erections and another purpose of the dancebelt is to maintain extra support control thus helping prevent embarrasment.
If your boys still balk after wearing the dancebelt and tights for a few hours tell them that they will have to go ahead and take ballet and wear the gear because most ballet stores will not accept returns for worn clothing.
Besides, once they go to their first class and see other boys wearing dancewear their fears should subside. However, if they are the only two guys in the class that means they will probably have many girlfriends because girls do like guys in their classes and in tights.[/i]