[Jacob-list] color genetics question

[melody]

I have been trying (with various degrees of success) to follow and
understand the postings on genetics--fascinating to me.  Now Fred's posting
about dominant black and breeding to self-colored sheep gives rise to a
question.  What if the Jacob in question was a lilac?  Are these not
considered "true" Jacobs? Do lilac Jacobs have the dominant black gene in
there somewhere? (you can tell I need to take a class in basic genetics).  I
ask because my only non-Jacob ewe, a dark brown shetland, was bred to a
lilac Jacob ram, and gave birth to twins yesterday --one black with white
markings around the face and a white smudge on one side, the other has black
legs but the body is black spots on a white background very heavily freckled
with black.  So by the definition, then, since the offspring are not solid
black, the lilac ram isn't really a true Jacob?
Confused in Redmond
also known as Melody