petite-pumpkin:

Well, I don’t know if it’s really a fact, but I head about this once and think about it sometimes?

When deaf children are still learning sign language, sometimes, instead of using the conventional sign for dog, they will pat their legs.
That’s because they have seen people trying to get a dog’s attention by patting their legs, so from watching that the kid will assume that gesture is the sign for dog.

I don’t know if it’s right, but I think it’s very interesting!