When everybody shows their superflat lands, you can see that the sheep are all white. But outside my home I was gone with my enchanted Diamond Sword. I killed some slimes for fun. When I came closer to the sheep the sheep was brown! I hit it with a diamond sword and it drop 1 brown wool. And then on my way home I saw a light gray sheep! How would those natural sheep spawn with a different color in my land?
White sheep - 81%
Light Gray - 5%
Grey - 5%
Black - 5%
Brown - 3% (50% in extreme hills biome)
Pink - 0.164%