I recommend this link to this informative Wikipedia article on Nativity Scenes:
As I believe I've said before, I have some passion for this subject. Since I was a small child, the Biblical story of the nativity (even in the King James Version) always touched me, frequently bringing me to tears. Over many years I've collected Italian nativity figures (Fontanini).
The Wikipedia article confirms a couple of points I've tried to make here:
1) Nativity Scenes are expansive and inclusive. Traditional nativity scenes may be as small as the baby and his family, but often expands to include the animals in the stable, the shepherds, the Magi (who really didn't arrive in Bethlehem until two years after the birth according to scripture.) Angels played a part in the biblical story and so they are often included as well. Of course, the angels sing of Christ's significance to the whole world, and so the imagination easily includes all earth's inhabitants in the scene. Wikipedia describes Nativity scenes with hundreds of figures sometimes representing hundreds of different animals and folks of all walks of life.
2) Wikipedia points out that the Nativity Scene tradition even includes the profane and even the scatological (read the article all the way to the end). By no means are all the figures in the Nativity Scene occupied by "adoring the Christ Child"--most of them are going about their ordinary business. That is also the case with the Italian nativity figures that I collect--I have shepherds lying in the field with their sheep (horrors!), musicians and dancing girls (one in a red dress!), Roman soldiers, people selling their wares in the market, a school boy at the feet of a Rabbi, etc. etc. etc. It is my sense, grounded in this tradition, that the Nativity Scene breaks down any notion of division between the sacred and the profane. Theologically speaking, the purpose of the incarnation, the coming of God in the form of a poor, homeless baby in a barn, is to break down the division between the divine and earthy, making all of life holy.
3) I hope this helps you to understand why I was offended by the "furor" over the inclusion of the same-gender couples in the nativity scene. Unfortunately, our adversaries in the Christian tradition seek to deny that we have any place in God's creation, and thus they justify our exclusion from marriage, from political equality, from ordination in the church etc. etc. etc.