Hi, My house burned down recently in Minecraft without being lit, what can be the cause?
Lava.
It wasn't
There are monsters that can throw fireballs, the hot Gost or something
If you don't have a fireplace it was 100 per flash
By lightning.
Lightning…
Sufficient even if the nearby strikes…
Probably a flash of lightning during a thunderstorm. When you play online, someone may have set fire to your house. What else is not possible in the Overworld without help.