None of my boys have expressed an interest in getting their ears pierced yet, but I suspect when DD eventually gets hers done at least one of the boys will want one pierced. I certainly wouldn't say no to them based on their gender, and yes to their little sister. The after school care teacher at their school has lots of piercings and brightly coloured hair so it's all pretty normal to them. DS2 in particular looks up to him as a bit of a role model so I wouldn't be shocked if he wanted his ear pierced to look like him.

ETA just asked my husband for his opinion, and he agrees with me that he sees no reason for boys to be older that girls in order to get their ears pierced.