Yeah, I've read that men in certain professions tend to have girls
more often than boys, due to the clothing they wear, or the conditions
in which they work:

Military pilots (the flight suits they wear tend to keep things
warmer)
Scuba Divers who wear wet suits frequently (same reason)
Truckers (sitting for hours on end tends to keep things warmer, as
well)

Cathy Weeks
Mommy to Kivi Alexis 12/01

Men my husband work with tend to have boys. The radio- or micro-waves kill
girl sperm. When I got pregnant with Charlotte he was not around those
waves