To some extent this is a trap question. I'll do my best to answer it fairly, however.
Simple reponse: yes, I think God does have children who do not
yet have His nature, key being
yet.
Allow me to open a can of worms. I'm firmly convinced of something that is unorthodox, but which has great bearing on this conversation, albeit indirectly. I do not think it is biblical to speak of anyone (yes, ANYONE) as being "saved" in the present tense. No one will be saved until the day of judgment, when the sheep and the goats are divided to the right and to the left. I've got an incomplete study on a "new" blog of the biblical use of the Greek word for "save" that I will link for those wishing to peruse it. Please remember it is incomplete and I know that:
http://www.christiantheologyessayist.blogspot.com/
As for when we are saved and how that relates to the present discussion...
I am convinced that we are saved from death and not from sin, and further convinced that this can only be true in the sense that we will
one day be saved from the second (final) death. Only once we are saved from the second death are we given our glorified bodies, and, I would argue, only then do we have a nature like His...not able to sin. Until then we have confidence in Him, in His goodness and His promises, so that we are able to have assurance that on that day we
will be saved. It is in this sense that, as we do not yet have His nature fully, we are now children of God, but not in the fullest sense as will be realized at a future time.