Explanation Desired: Zodiac Signs

I'm usually a critic of things that look immediately hooky. Send this to eleven people and I'll have good luck? Not for me. But for a good part of my life I've had some confidence in astrological signs. I don't abide by daily/weekly/monthly horoscopes (now these I think are untrue) but personality wise? The descriptions are strangely accurate.

For example, I'm a Virgo and proud of it. Most all of the characteristics that Virgos are said to have I certainly have.

I once told my dad about astrological signs. He made a really good point: he said that you could read any of the twelve astrological descriptions without seeing the name at the top and identify with it. This point makes sense. If I see another personality profile for, say, Aries, but I don't know that it's Aries , I could probably say to myself, "yes, I am adventurous." But I've looked over the other profiles, and I do feel like I identify several times more closely with the Virgo descriptions. I'm analytical. Hard-working. Perfectionistic, sometimes too much so. Reliable. Fussy.

Even scarier is the description of personalities of people born on my birthday: "Extremely creative, you are also able to turn your creations into something practical. A born entrepreneur, you seem to have endless new ideas. A tendency to over-analyze your relationships should be watched. While you are fully capable of taking the lead, nevertheless you enjoy serving in some manner, whether it's through teaching or simply finding joy in tending to others' needs." I found that scary in its accuracy.

So the real question is not whether or not astrological personalities were accurate but why they were or weren't. People argue about electromagnetic forces and such, and I'm not sure what to believe on that front, but I would think it would have something to do with parenting. It might sound like a weak argument, but there are bound to be correlations in parenting based on the season that pregnancy and birth occur.

I tend to find that zodiac signs most accurately describe a person born closer to the middle of its date range. For example, Virgos are those born between August 23rd and September 22nd. A person born on September 10th would be more likely to display Virgoan traits over someone born on August 24th. Those around August 21, 22, 23, and 24 would probably be a combination of Leo and Virgo traits.

While I can make the ambiguous argument that personality could have something to do with seasonal time of birth, I can't explain why people born on the same date (as in, two people born on January 5th and July 5th) would have anything in common. Seasons are natural; dates of the month are not, especially since not all months have the same number of days. Said about my birth date:

"Being born on this day of the month should help make you a better manager and organizer, but it may also give you a tendency to dominate people a bit. Sincere and honest, you are a serious, hard working individual. Your feeling are likely to seem somewhat repressed at times. Even if it by itself, you are apt to be much more practical, rational, and conscious of details. Your intolerance and insistence on complete accuracy can be irritating to some. "

Also quite true, and of the other people I know born on the same day of the month, this is pretty true. But I have a feeling that this is based on "confirmation bias," or the concept that my dad had introduced. Maybe I believed it because I wanted to.

Is your zodiac sign an accurate description of your personality? Why might astrological signs be pretty accurate?