The SDN forums are very supportive, and yes, there is no badmouthing, being catty, etc. That's not the point. The point is that you reveal a little more about your personal life that may or may not be detrimental to how you want to be presented, even though adcoms are supposed to be unswayed by personal biases. It's up to you if you want to reveal that, but just know that some things can be turned around into a negative, especially out of context.
And it's true. Most adcoms probably have no time to surf SDN to find out all the dirt on applicants. But why add that extra miniscule amount of stress? In light of competition between candidates that are equally as qualified for a seat, it does seem arbitrary how some schools ended up rejecting and admitting students. I, in my fit of paranoia, wouldn't want something as dumb as a forum post to tip the scales out of my favor.
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You know, after typing all that up, it does seem silly to have revealing your undergrad = your downfall. I think I'm just going into conspiracies and worst-case-scenarios. I'd still err on the safe side, even though posting anywhere online results in the same risk. Oh well. I'll go back to studying my hind limb now 🙂