Anyone know the ages of the Actors

I was wondering the ages of the main actors. (Jerry, George, Kramer, etc.)

Jerry Seinfeld (Jerry): New York, N.Y. 4/29/55 Jason Alexander (George): Newark, N.J. 9/23/59 Micheal Richards (Kramer): Culver City, CA 7/14/50

I wasn't able to find out Julia Louis-Dreyfus' age for some reason but I suppose she is around the same age.

Elaine: January 13th, 1961 Manhattan, New York

The spread on the ages is consistent with Jerry, George, Elaine and Kramer being sibs. They act like they are most times.