Yes, it's alright to ask. It's then up to the T whether or not she chooses to answer. With my T, if I ask her a personal question that is related to the topic at hand, she'll pretty much always answer. For instance, after discussing what characteristics I'm attracted to physically in another person, I asked her: "Well, what about you?" She answered the question. I also asked her once who her celebrity crush would be (after telling her mine) and, since she didn't know off-hand, she came back the next week with a couple of names. My T's philosophy is that it really depends which client is asking her the personal question, why, and how it relates to what they're working on in therapy.