I guarantee you could replace "Zodiac" with "was it sunny or rainy the day you were born" or "what letter does your first name start with" and you'd have the same barely-there correlations with anything (because nothing is ever 50/50).
Confirmation bias isn't sane behavior, and astrology, Zodiac is so boring compared to the real stuff as it is. I swear a good portion of believers know it's bunk but it's an easy simply fun relatively harmless superstition to have.
Oh, and Libra/weed.