One parent is always hot, the other always cold. How do I resolve?

I appreciate the advice. And if I can get either of them to follow it, maybe things would be easier. Mom is slightly overweight, and Dad is slightly underweight, but both are active. Dad does have his "man-cave" and holes up in there for hours each day. Trying to get him to come out and be social is a chore already, made more difficult by the temperature differential.

Layers work well when I visit cold climates. The equivalent of cuddle duds are available for men. Also the puff jackets and vests which are popular now are very light in weight yet they are warm. Both their thyroids should be checked. Make sure dads nutrition is adequate. I read once that it takes at least 800 calories to warm the body. If dad is sitting too much he might not be circulating his blood. If mom is still doing house work, cooking and moving around more and dad is " retired" and watching a lot of tv you can see how that would create a different requirement for the thermostat setting. Remind mom to drink ice water and make sure she doesn't have a fever. She might be drinking hot drinks excessively. Check their blood pressure out as well. Has either started a new med? Some people tell me chocolate will make them have hot flashes. Is there a time of day they are more likely to be uncomfortable? After eating? After exercise? Ask them to pay attention to when they are uncomfortable. What was going on? Is mom overweight and dad underweight? Good luck with your detective work.

Do they live with you Cybotic? If not I would stay out of the middle of that fight, it has probably been going on for years.
I think the best strategy is to try and create different areas for each of them if possible. Set up a "man cave" for your dad in a spare bedroom and furnish it with comfy chairs, tv and a space heater, leave the rest of the place at a more comfortable temp for mom (and probably everyone else lol).

The trouble is that the parents need very different temperatures to be comfortable.

It's a lot easier to bundle up (for the cold one) than it is to cool down for the hot one. So get dad some sweaters, leg warmers, insulated pants, jackets, a heating pad, an electric blanket, whatever it takes to warm him up. Let mom be comfortable! (Said as someone who is frequently hot, LOL!!).

There was an identical question posted sometime ago. I was unable to locate it, but the first 3 and the fifth threads from these hits might be of help.

https://www.agingcare.com/search.aspx?searchterm=one+parent+hot%2c+one+parent+cold

They will provide insights into why different people feel cold and warm while in the same environment.