Gluten Free Eggnog
All Eggnog is Gluten Free
Good News! All major brands of Egg Nog are naturally Gluten Free! Wheat is not something to add in any recipe for Egg Nog. (I am sure someplace there's an Oreo Egg Nog and that's definitely not Gluten Free!)
I checked Hood, Garelick Farms and they both have their entire Eggnog product line as Gluten Free.
Turn of the Century Recipe
I found this "Turn of the Century" EggNog recipe at the Boston Public Library (January 1922). This is how your grandmother might have made EggNog.
Beat white to a stiff froth, then put in the yolk, beat very light, and bring milk to boiling heat and pour over the egg, then add sugar and flavor.
If this, is not your recipe please try and see how superior it is to the old way.
I am not exactly sure that's going to taste the same as people might have gotten used to. I will continue to look to see if there's a more detail "Turn of the Century" way to make EggNog.