I'm writing a story about furred¹ sophonts. (In this instance, humanoid, although I don't think that affects the answers.) What I want to know is, to what extent would they still "add layers" (either clothing or blankets) to keep warm (or cool)?
On the one hand, wild terrestrial mammals obviously get by without clothing, for the most part. (There are a few "exceptions", such as pigs and elephants covering themselves with dirt, but that's more for cooling, whereas I'm mainly focused on keeping warm.)
On the other hand, clothing helps humans to more readily adapt to a wide variety of climates, and we do provide blankets for e.g. horses. Also, I've read that human children have a harder time keeping warm than adults, and am wondering to what extent this applies to animals. Certainly, animals that are smaller than human children can manage just fine in some pretty extreme temperatures (e.g. arctic foxes).
What I want to know specifically is, would children of a furred sophont species need clothing or blankets to keep warm, especially when sleeping, in a 'partially'¹ climate controlled environment? Would they be too warm in anything but light clothing? Or would it not make much difference? If clothes / blankets are needed, do younger children need more supplemental insulation and/or at what age would they be able to sleep 'in the buff'?
(¹ To clarify — with apologies for possibly mucking up Justin Thyme the Second's answer — they are mammals, with the usual traits as we would define "mammal".)
(² I'm assuming that, because they are furred, they are less tolerant of drastic changes in temperature, and so they don't heat / cool their houses as much as we would so that a) it's easier to go from indoors to outdoors without putting on or taking off as much clothing, and b) they can grow thicker coats in winter without risking heat-stroke indoors. Accordingly, I am asking about indoor conditions at a temperature of around 15°C / 55°F - 60°F. Note that 'indoor' also means no snow/rain, no wind unless they create it using fans, etc. Imagine your own house, but with the heat cranked down as if you were on vacation for a few weeks.)
p.s. Ignore the classic snark answer. Obviously, they'll have something for utilitarian purposes. My question is more to what extent they can do without it, especially when they're sleeping. (If you're asleep, you don't really need pockets... and you don't really want things in pockets. Like us, they'll keep their smart phones on a nightstand.) I am focused on thermoregulation, and how it would vary by age, rather than any other useful properties of clothing.