Does a mix breed take longer to grow than a full breed?

my dog is mixed with a german shepherd and a rotweiler and it's kinda small for its age.

Well, considering it's a mutt, no one really knows. It's a mystery.

nopejust bad breeding.

no mixed breed dogs do not take longer to grow.

Large breed or mixes grow slower than small breed dogs. I have a Maltese and she was full grown at 9 months. I also have a 10 week old Anatolian Shepherd who will not be full grown (125-140lbs) until she is about 3 or 4 YEARS old.

No breed doesn't influence how long they take to grow. It could depend on whether the german shepherd and rotweiller were pure breds or mixed themselves.

It could be that somewhere along the line there was a smaller GSD or smaller Rottie in the mix. Not all of them are huge. Or perhaps a smaller dog of another breed in it's lineage?

No, they're normal.

growing dogs are just like growing people...everyone is different, and averages don't tell a story's details. talk to a vet if you want it to grow big and healthy, but you can't rush it safely.

No..why would that matter? there are alot of poorly bred GSD and Rotties that are small, and who knows there may be another daddy in the mix.

All breeds grow at different rates. It is impossible to tell when your dog will reach its full maturity due to the mix of breeds. The larger breeds tend to fill out completely later than the smaller breeds.

It depends. Keep in mind that different breeds grow at different rates. A German Shepherd remains a puppy much longer than most breeds. Even though a German Shepherd is already huge by the time it's 6 months old, it's still growing and maturing rapidly. A German Shepherd doesn't reach it's full physical or mental maturity until after 3 years of age. The Rottweiler is a large, slow-growing breed, and won't be considered 'mature' or fully grown until he/she is at least 18 months to 2 years old.