"The question not as "is Astrology real or correct", it becomes "could time of birth affect development, apart from seasonal effects?"

I have wondered that too. Trouble is: signal-to-noise ratio. Maybe you were born in December and it was cold, so you have a slight tendency to think of the world as hostile (say).

But that will be drowned out by a zillion other far-more-important influences.

Same a fortiori with gravitational/electromagnetic fields. Start with gravity. I calculate on the back of the envelope the pull of Proxima Centauri (the nearest star that's not the sun) as being on the order of 7 piconewton, or 7 trillionths of a newton. (A newton is enough force to lift a hamburger.) So what if you are pulled in the direction of P. Centauri by an amount as feeble as that? That's about as much gravitational pull as an orange has on you 50 metres away. :) Not to mention all the other stars are acting in opposite directions. Result: nil.

Electrical force argument left as an exercise for the reader.