I took some fairly high level genetics coarses in post secondary and while that was a long time ago, i remember looking at calico cats (white/black/orange) and how they are all female.
As it turns out, some chromosomes go into a state knows as supercoils and form these barr bodies Johnny referred to. A supercoiled chromosome can not express its gene code.
So the female cats have 2 X chromosomes in every cel (each one referred to as an allele) and apparantly one half ( or one allele) would coil up an the other half would be available to express what ever gene code was there. As an example, one X would code Black hair, the other X would code white, and if neither were supercoiled, then orange was the product of that gene sequence.
thats a super simplified version...if thats the mechanism for marbling in springs then all marbled springs would be female.
Coinsidentally, the one marbled spring I have seen was a female! If indeed the enzyme needed to absorb caroteen (I think) is on the X chromosome, the yes jonny you are right. I wil see what I can find.
Here's a link for the text book version of calico cat genetics:
http://www.bio.miami.edu/dana/104/calico.html