What genetic advantage is there to being tall in a cold climate?

I agree with you. Being tall offers no advantages to living in a cold climate. The Neaderthals had a larger body m. But they had hundreds of thousands of years to adapt to the cold weather of Europe. Modern humans are recent arrivals to Europe. They've only been there for tens of thousands of years. Humans living in Scandinavian countries have been there less than 10,000 years. The last ice age ended 10,000 years ago. During the ice age, Northern Europe was covered by a giant ice sheet, and was uninhabitable. Scandinavians themselves are Germanic, and have only been in Scandinavia for a couple of thousand years.