I get mixure of male and females. i find it funny that my problem is that my mice mutliply fast but they never get large. All my rodents have more male to female ratios. I always feed all but 2 males off and end up feeding the adult male off and end up with random litters after that never had much luck of a steady breeding. some times they breed and then kill all th youngoff like they preventing me from reducingthe numbers cause they not repalceing themselves enough.. ( am going to take my oldest tank and offthe lot and aquire new ones this spring my luck I make the arrangementss and they all drop babies )