I mean, right, it's astrology, so its real-life impact is nonexistent, but people's reactions are really interesting. Most people are some variation of "What, so I'm an X now? No way am I an X!" (I for one find what I hastily learned from one random website about Aquariuses to be much more accurately descriptive of my personality than the wishy-washy touchy-feely dreamy fish I was previously purported to be, not that that matters.) I really hope people's reactions to just staying what they've always been are due to this all just being fun and games and changing exactly nothing about the real world; otherwise, these attitudes of "What I've always 'known' above all else!" are rather terrifying.
For someone who took astrological claims seriously and truly believed the positions of the stars in the sky at one's birth actually influenced or outright determined their personality, fate, and compatibility with others, there would be no choice but to accept this new knowledge immediately, switch to the "new" sign, and live as that which they always were, despite having been misled in the past. I'm not terribly familiar with astrological claims, but I assume there is supposed to be some mechanism by which these positions affects people above and beyond their knowledge thereof. So, pretending this was somehow scientifically valid, it doesn't matter what you think you are or what you've always been, the only thing that matters is which constellation the sun was in at your birth. Denying, then, the "new" (actually it seems to have been known since before the Common Era that the alignment of constellations and dates were drifting through an epic cycle) and apparently earthshattering news that you've been wrong your entire life about something so important would be counterproductive and the worst possible response. The only reasonable response would be to adopt your real sign as quickly as possible and try to make up for years of living your life a little out of sync thanks to heeding advice meant for others. But no: "I've always been an X!" "Screw you, I was born a Y and I'll die a Y!" "Z forever!"
Obviously in this case there are two levels of truth. "I was born a Leo" means either (or, until today, presumably both) that one was born when the sun was in the constellation Leo or that one was born on a date that was considered to belong to the sign of Leo. We're learning that the former expression is now untrue for many of us, but people's vehement responses are obviously because the latter expression turns out to be the most important to them in a visceral sense. And I suppose that's reasonable, since we do live in a society in a time period that (at least I assume I'm not extrapolating terribly, though as it tuns out, 25 percent of Americans believe in astrology) is too sophisticated to believe in such primitive nonsense. So of course cultural categories matter more than "reality" in this case, since the reality is impotent either way. Not that the cultural categories aren't, but as far as spending your life half-heartedly identifying with some set of characteristics or reading horoscopes in the hopes they'll have something useful to say about your day, I suppose there's no more reason to disrupt that for these scientific reasons than for the scientific reasons of oh wait, they're stars, exactly how are they supposed to affect your life?
Regardless, I certainly hope if, in the future, we are presented with new scientific knowledge that asserts what we've been thinking or doing our entire lives and/or history is incorrect in some area where it might actually matter, we'll be a bit more open to it and not cling to our past beliefs so tenaciously. Unfortunately, that doesn't seem terribly likely. I'm reminded of the Pluto debacle, although that was less about new information and more about consistency in categorization (also it probably doesn't make any difference to anything real how it's categorized). But there's the babies-on-their-tummies versus babies-on-their-backs vacillation and the fat-is-bad—no-wait-carbs-are-bad debate, and I'm sure there are plenty of other life-changing discoveries to come. (Though in both of these cases I think we've held each position more than once over our history, so the problem seems to be either in changes in how we measure outcomes or in properly designing and analyzing studies. I guess when scientific consensus changes that much (or doesn't actually reach consensus) in one's lifetime, it's harder to feel certain that this time it's right, so personal choice and preference does actually seem to be (and may be, for all I know) a valid way of making decisions above and beyond the evidence.) I think these habits of disregarding evidence and relying on our intuitions, wishes, or anecdotal evidence bode ill for our nation as a whole and the state of ourselves and our minds as human beings.