There is evidence for birth-order influence of a fetus' genetic development. [1] When a mother has a male child, subsequent male children may not receive the same developmental antibody responses.

The time we spend gestating has a huge effect on our development and is completely independent of the "momentary genetic dice roll" that happened immediately previous.

[1] Sources referenced in the index of Matt Ridley's 1999 book "Genome": Vines, G (1997). Where did you get your brains? _New Scientist_, 3 May 1997: 34-9; Lefebvre, L., Viville, S., Barton, S. C., Ishino, F., Keverne, E. B. and Surani, M. A. (1998). Abnormal maternal behaviour and growth retardation associated with loss of the imprinted gene Mest. _Nature Genetics_ 20: 163-9.