One example would be in Asian cultures where someone's education and experience are highly valued. In such a culture, mentorees may be reluctant to ask for more time or to share a great deal of themselves due to the assumption that to do so is to impose upon a mentor's valuable time. There is a fear of being a burden to one's mentor.
Under these circumstances, it is important that the mentor take the initiative to express his/her desire to learn more about the mentoree and to indicate that by the mentoree sharing his/her experiences, knowledge, culture, etc., the mentor gains as well. This means the mentor may have to actually ask questions that explore the mentoree's background and culture - not in an intrusive way but as a way of learning about and understanding the mentoree better. For mentors in these types of relationships, it is easy to misinterpret a reluctance to share on the part of the mentoree as simply being witholding when what is really happening is the mentoree being deferential to the mentor.
Cultural nuances do impact mentoring and since mentoring is about a relationship, it's important for all of us in such relationships to learn about the other partner..not just by asking questions but by exploring resources that can shed light on the cultural background of the mentoree or mentor. Picking up a book that deals with cultural differences or going online to explore the specific culture of your partner can provide valuable insight into how best to communicate and engage as a pair.