I don't have an answer about people with IQs of 176, but I *can* add two observations:
1) People are lazy, and don't like to take people on their own merits. If they can find a reason to discredit someone's opinion. character, or intelligence, or character, even if it has nothing to do with the topic at hand, be it age, religion, orientation, etc, they will. It's easier to dismiss somebody when they're gay, or atheist, or sixteen, Welsh, or whatever they happen to be, than to actually consider someone's opinion seriously, or even treat them with common decency.
2)Individual people can be really kind and nice, but people as a group tend to be rude and stupid towards others, especially on the Internet. In the offline world, if you're rude to someone, you can get yelled at, punched in the face, or at least feel bad (assuming one has at least a particle of decency in him or her).
Online, such consequences don't really exist, so the tendency to be a jerk to others is given free rein (at least for people who don't have enough of a conscience to be decent to people, even online)
What does this have to do with this question? It has more to do with the fact that most of the responses to this questions are examples of the two observations I'm pointing out. People are being lazy-minded, preferring to dismiss someone because of her age, and being jerks online because they don't have to worry about getting punched in the face by a user on Yahoo! Answers. If somehow, you COULD get punched in the face on Y!A, it's likely that there'd be a lot of bloody noses, and a lot less rude people on it. And kudos for those who've actually given a serious answer and didn't let their inner jerk take them over.
-Jon