vector distribution

Hi everyone, 

say i have a population (stable) with different amounts of animals in every
ageclass (80 of age 1, 60 of age 2, etc) in a vector.
Can anybody tell me how i can add gender (male or female) to all ageclasses?
I want a 1:1 ratio of males and females within the population (as a starting
value). So, 40 males and 40 females of age 1, 30m-30f of age 2, etc etc... 

Any help would be greatly appreciated!! 

Kind regards

x <- c(age1=80,age2=60,age3=40)
x

y <- rep(x/2,2)
names(y) <- c(paste("M",names(x),sep="."),paste("F",names(x),sep="."))
y