We all tend to accustom ourselves to the smell of our homes and not notice it.
I don't mean dirty homes: every house or flat I have ever been in had a distinctive smell and my house does too, but I only
notice it, if I have been away for over a week. Then it smells of home when I get back.
Most of us will notice if our body odour changes, but not everyone does.
Some time after my mother's death I noticed that my father smelled musty. I traced the cause to a face flannel that had been used too long and not dried out completely between daily use in an unheated bathroom. Towels too can turn musty and transfer the smell to a person's body. So can clothes that have dried too slowly in the autumn or winter in unheated rooms.
Smokers don't notice the smell of tobacco clinging to them, and cat and dog owners don't notice the smell of their pets.
There is only one way to find out: ask your sons what makes them open your window when you visit.
Obviously, they smell something, but it might not be you, it might be that they are smelling an unused guest bedroom!