maybe the season, cuz when i was a week old my parents took me to a thanksgiving parade and my dad put me in his coat to keep warm now i feel safe and secure in warm dark comfy places, like under loads of blankets curled up into a little ball.
Dates are arbitrary; there's no mechanism for them to influence personality. That being said, children who enter school at younger ages tend to suffer for it due to being smaller and less mature than other students, and kids born around Christmas or other major, annual events are sometimes impacted negatively as well. Further from that, being born during certain times (during war or a depression, for example) can have a drastic impact on personality.
As for the difference between MBTI and astrology, the former is descriptive while the later is proscriptive. They really can't be compared in a meaningful way.
A man builds. A parasite asks 'Where is my share?'
A man creates. A parasite says, 'What will the neighbors think?'
A man invents. A parasite says, 'Watch out, or you might tread on the toes of God... '
It's actually been proven that birth month can absolutely have an effect on you, like many external factors that are outside of our control.
In the book Blink by Malcolm Gladwell, he talks about the unusual birth month distribution among hockey players in Canada:
The first chapter in "Outliers" is about how some Canadian hockey players born in the first months of the year enjoy advantages that those born later in the year don't have. You also write that birth month correlates closely with success in other sports. Why is this?
It's a beautiful example of a self-fulfilling prophecy. In Canada, the eligibility cutoff for age-class hockey programs is Jan. 1. Canada also takes hockey really seriously, so coaches start streaming the best hockey players into elite programs, where they practice more and play more games and get better coaching, as early as 8 or 9. But who tends to be the "best" player at age 8 or 8? The oldest, of course -- the kids born nearest the cut-off date, who can be as much as almost a year older than kids born at the other end of the cut-off date. When you are 8 years old, 10 or 11 extra months of maturity means a lot.
In my experience, whenever I took advanced or honors classes, it seemed like almost everyone was born in December or January. Applying the same phenomenon from the Canadian hockey leagues, I would postulate that this is because that is the earliest you can be born before being held back a grade. Assuming all else is equal, if someone born in December was put in the same class as someone born in September or October of the next year, the one born in December would be several months ahead in cognitive development. This would probably lead to them performing better, and maybe they would be assigned to more advanced classes. This could lead to the students being treated differently. One would be the "smart" one and be pushed to succeed academically, while the other would have to find another way to differentiate themself. It's not difficult to imagine how this would have an effect on their personalities. This is all hypothetical, of course. Results may vary.