We live in Alaska, and I rarely put a jacket on my son
It's probably because people just get used to the weather they're in.
It's too hot for him. He only goes outside for a few seconds, so I just use a blanket. Lately he's wearing a jacket but I take it off before he ges in the car. He sweats too much! I wear my THICK winter jacket in the car with the heater on, and he's sweating... but only in a onsie, long-sleeve shirt, and pants. They have real cheap long-sleeve onsies at Wal-Mart. Stylish too!
And for sleeping, I keep his vent open, and the rest are closed in the house. As long as it stays around 69 in there, he's comfortable ...although they do say 72 is where MOST humans are comfortable. He sweats up a storm when it's above 70. I just go in and check on him in the middle of the night and turn the heater up or down based on if his hands and ears feel cold.
Last winter, had to wear a onsie, two shirts, a sleeper, and a pair of pants over that to stay warm at night. For some reason his room is the coldest in the house DESPITE it being the only vent open. Very weird.