Billy or nanny

I never know. By looking at a goat if it’s a Billy or nanny goat,
They are always a friendly and happy looking animal coming to the fence to have a look at you or running around the piece of the field that they are in.
It’s another bitterly cold day with a frost on the car windscreen, the forecast says it will be a high of only 1* and a low of -3* so it’s a case of wrapping up warm and plenty of hot drinks.