Understanding?

Is it possible to understand something without having the privilege of experiencing it first hand? Many people, while listening or talking will respond to a sympathetic situation with, "Oh I understand." But do they really? Can they understand without experiencing it. One may seek to understand, and are able to a certain extent, but is their understanding limited to what they have read or experienced through other people?

Let's say Bubble boy has lived inside a bubble his whole life. He has never gone outside to experience the world and relationships. He has had an adequate supply of books to read throughout his lifetime. Bubble boy has read detailed descriptions of what it feels like to be pricked by a pin, or the sensation of falling. He may get a picture in his mind and he may say he understands what it is like to be pricked by a pin, but would be really understand what it felt like without it actually happening to him?

So my question is: Can you fully understand something in which you have not experienced yourself?