Cheers and congrats too to healthy looking you & yr healthy mama. And yeah we're clearly on the same wavelength here. I agree with and like what you're saying re skin health being a good general sign of health. But also the converse - good skin health also helps general health, as it is obviously our protective layer but also how the body 'breathes' or perspires.
Re dry skin from Swiss climate, one thing I would say is that water is the 'universal solvent' (a good thing for washing) but its ability to strip away your skin nourishing sebum is markedly increased by 1) temperature of the water and 2) the water constantly running over the skin. So that means hot showers will dry out your skin the most while colder showers and hot or warm baths will strip away far less.
I did a year of only cold showers a few years back and something I soon noticed after I started the practice is that my elbows, which were a little 'grey' and dry (like a lot of ppl), soon became smooth and pink again. (Also my hair became brighter with many natural 'highlights' but that's another story.) So cooler water for showers and or swapping out showers for baths might help you to not even need the tallow (not that I'm trying to talk you out of it).
