Different sized rats with particular lines?

Hey guys, I was wondering if it's common for different bloodlines to be different sizes as adults?

I currently have 2 breeding pairs of rats. My BEW's which were purchased from a Mousery (large warehouse mousery) that breeds specifically feeders.
I also have a pair of high white Russian Blues which were purchased from a small rattery that breeders just for pet rats.

I noticed my BEW's were a bit bigger as adults than the other pair but I was really shocked of the size difference when I paired up the BEW male with the high white Russian Blues girls.
http://i116.photobucket.com/albums/o...24/photo-1.jpg
The female in the picture (the blue with her hands up on the water tube) is over 6 months old and (I believe) fully grown. The male is about 7 months. I know males tend to get a bit larger than females but he is almost twice her size. Is it common for different bloodlines to be this different in adult size?

It isn't uncommon for there to be such a severe difference in the size of a mature male, and a mature female, which is probably the case here. Just different sexes growing to different sizes.


But yes, different lines produce different sized rats.
Just like different lines of everything else do the same.

I don't have a good rat example photo, but here is a photo example of the difference between a show mouse, and a normal fancy mouse. These mice are the same species, just very different breeding went into each one.
http://i42.tinypic.com/2q9l98z.jpg

Hell I even have different sized adult rats within my own colony.

Meaning they are say, smaller adults or larger adults, and are the same amongst the whole litter they came from if that makes sense.

I even have fast growing liters and really slow growing litters.