Two of the three legitimately oversized (not fat) border collies we’ve had were both curly furred and stocky.  Their muzzles were also more squared & boxy than is typical.  
Both were purebreds with siblings who were more breed typical, so I can only assume it was some recessive genes expressing themselves.
The third one was actually our first border collie ever, and was more like that one pictured above- almost like a funny looking German Shepard.
Alas, SHE was a nutcase. She thought she was the last line of defense between our family and the universe..and she wasn’t too sure of us 100% of the time. Didn’t like human women except my Mom and her younger sister. Her aggression got her killed when she bolted out of the house past my Mom and attacked a passing car. At that point, she was only 6 months old and over 55lbs.
				
			Both were purebreds with siblings who were more breed typical, so I can only assume it was some recessive genes expressing themselves.
The third one was actually our first border collie ever, and was more like that one pictured above- almost like a funny looking German Shepard.
Alas, SHE was a nutcase. She thought she was the last line of defense between our family and the universe..and she wasn’t too sure of us 100% of the time. Didn’t like human women except my Mom and her younger sister. Her aggression got her killed when she bolted out of the house past my Mom and attacked a passing car. At that point, she was only 6 months old and over 55lbs.
 
				 
 
		 
 
		 
	 
 
		 
			 
			 
			 
			 
			 
			 
 
		 
 
		 
 
		 
 
		 
 
		