My male Rats are 6 months with no balls! Are they boys?

[Eboni R]

I got my "boys", Leo and Elliot, at Petco in August of last year. They were in the male tank and I did not ask questions. Everything was fine until I got another male rat in mid December. I knew they were going to be doing their dominance acts on each other to figure things out and it then that I noticed that the new rat, Mr. Bojangels, had balls while my rats had none. Bo would chase the "boys" around and hump them. They would fight back but after a few introduction a week, Elliot would stop fight and just run up to Bo and then be chased, be humped, then run back to him, run, and repeat process. Now yesterday, Leo, who is usually the one who stands his ground against Bo, started letting Bo hump him! They are all the same size but Leo and Elliot have no balls not even numbs...but my "boys" do have nipples while Bo none..I have done some research but its had to tell. Bo gets so excieted with them and the "boys" either try to scratch him through the cage or run around from him and let Bo hump them. Is this a phase? Are my "boys" really Lisa and Ellie? DO some male rats take a year for their balls to drop? Please help! I dont want babies!