Mum taught me. I would have been about 11. But hers was not like the American style. She learned while traveling in France. Only one side is cooked. The key is a special omelette/crepe pan which has extremely shallow curved sides. It needs to be sizzling hot and well lubricated with butter (or olive oil or ghee.) Beat two fresh eggs with one tablespoon of milk, a pinch of salt and 2 pinches of freshly cracked black pepper. Pour the mix into the sizzling butter and sluice about till the pan is covered and the lower layer of egg is just solidifying and turning golden. At this moment one can add other ingredients, such as camembert &/or fried mushrooms, placing them in a line along the gooey center. Serve by slipping from pan to plate and as it comes off, flip the omelette with one third folding over the centre, then use a spatula to fold the other third back over the top. Serve sprinkled with lots of finely ground fresh parsley.
The way Mum showed me made it very simple and I succeeded on my first try.
I've always made them as long as I can remember (as an adult). I used to flip them, and often made a bit of a tasty mess. I eventually bought an omelet pan and have enjoyed it; it makes it foolproof. I like ingredients like peppers, onions, cheese, mushrooms, ham.... An omelette is a dinner food, not a breakfast one for me.