Jacob creating flocks of speckled sheep by having non-speckled sheep drink from a trough which had a speckled branch placed in it.
Yes, all the pure white sheep who drank from this trough went on to produce speckled sheep that he could keep.
The gene changing properties of a speckled branch.
Jacob should have filled the trough with insects as well, to give all of the sheep six legs. Sheesh.