As a sensible grounded type of person my stance has always been no obviously it's silly, but the fact is I fit my sign (Virgo) perfectly and ex girlfriends have also fitted their signs, so I just put my fingers in my ears and go la la la la la it's not true.
No. Considered the fact that they haven't taken into account how the stars aren't in the same place they were in the sky thousands of years ago when they came up with the idea.... even if it was originally "real", it isn't now. Not to mention - why would it matter how the stars were aligned when you're born... you'd already been in the womb for 9 months. Physically still surrounded by the same universe you were when you came out (give or take a few layers of flesh). So shouldn't it be based on how the stars were aligned when you were conceived?
While I don't believe in astrology per se (with zodiac signs and all that), I think that the time of the year you're born in has an effect on you.
As we associate your birthday with a certain period (blooming early spring, laid-back heart of the summer, melancholic September...) it probably affects our personalities subconsciously as well.