People sometimes ask personal questions because curiosity feels like permission from inside their own mind.

Wanting to know feels, from the inside, like being allowed to know. The interest is genuine, often affectionate, and it comes with no awareness that a line is being approached, which is why intrusive questions are so often asked by kind people. Nobody is checking their own curiosity against your comfort. That check is yours to perform.

Remember that an awkward question is usually not an attack, which makes it easier to decline warmly rather than sharply. Give a short non-answer and move on. Most people take the hint immediately and no harm is done.