i'm torn on this one.
as for myself, it wouldn;t bother me in the least. my daughter and i have played house using two mommies or two daddies, and it doesn't stop there; we try to teach her tolerance in all things (and will with the tiny tyrant when he's old enough to get it and we do now, i suppose, just by the very nature of the way kids learn through observation.) but the school, knowing that this is a highly charged and sensitive topic, pulled a fast one. they didn't read a story about gay bashing, and, that's "part of our world", too. (although i suspect some of the parents wouldn't have minded that one so much

). so their reasoning is a bit faulty.
on the other hand, when parents begin (as seems to be the trend here in the US) handing over more and more of the
raising (as opposed to just the education) of their kids to teachers, then it's up to the educators to step up and take responsibilty for producing an entire generation of kids who will use their powers for good, not evil. and parents need to sleep in the beds they've made.
heinous is much too strong of a word, and the argument that is was sex-education (and therefore required notification) is ridiculous but poor judgement on the part of the educators? yeah, i think so. it wouldn't have taken a whole lot for the teacher to give the parents a heads up beforehand and let the parent(s) decide whether or not to let their child hear the story. i think it was more of the sly, neener-neener-neener, overtones that has the 'rents pissed off. nothing like coming home from work and getting macktrucked into a convo with your little-one that you maybe weren't prepared to handle at the moment that will get those hackles up. not to mention there are religious beliefs that would make this a taboo subject for many. if we are permitted, indeed guarunteed the right, to worship (or not) as we choose, then how can the school just step all over those beliefs by "forcing" parents to talk about it.
quite a conundrum.