If you really wanted to look for a potential factor it would be cosmic particles. They are passing right through us all day and all night, passing through the latticework of atoms like tennis balls thrown through scaffolding. They do, very occasionally, hit the structure.

The trouble with linking cosmic particles to astrology is the fact that we are indeed bombarded with them at all times, and that makes a nonsense of the importance attached by astrology to the exact time and place of birth.

It was obvious for some weeks before he was born that my son was a considerably more laid-back baby than his older sister. That there is some sort of cosmic significance to the moment of birth-by that point in development not much more than a (traumatic) change in environment-doesn't make logical sense. How could cosmic particles or forces acting across vast distances be stopped dead by a few centimetres of flesh and amniotic fluid?

Birth time isn't calculably related to the moment of conception with any great accuracy-there's sufficient variation in gestation period that only about 5% of babies are born on their due date.  On a cosmic scale, even within the scale of an individual life, there's a four-week period within which the moment of birth is as near arbitrary as makes no difference.

Unless we postulate that the time of birth is influenced by the guiding stars.  But my own birth was induced early when my mother developed pre-eclampsia.  It altered my star sign, but a generation or so earlier we would probably both have died.  For cosmic forces to account for relatively new medical technology implies a level of predestination rather incompatible with any notion of free will.

Well done for bringing a touch of astringent rationality to the discussion TBG :-)

Maybe it's because I'm a Londoner - that I moved to Nice.

Do unemotional people have less water in their bodies than moody people?

great question!

here's an 'indirect' answer:

people with a lot of water in their charts are definitely moodier/more emotionally governed, in my and many others' experience.

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty

Argument by Analogy is always suspect and tends to become an Informal Logical fallacy when it is the only Argument in the ... uh ... argument.  

As a heuristic tool to start an investigation it can be quite fruitful.  

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre

Maybe women are more attuned to the moon cycles. Before the pill, a \"normal\" menstruation cycle used to be 28 days, and the amazing thing was that many women used to menstruate during the full moon period. Native American women had their moon lodge were they used to go during that time. Same stories can be read about women from other native people in other countries. Now with the pill, it seems women are not as synchronised with the moon anymore.

Oh, and just pay attention to traffic on a full moon day! :-) you know all those lunatics loose in cars.