This question, a staple of newspaper and magazine interviews, may be becoming irrelevant, as fewer young people buy music.
Take this answer from Misha B, ex of the X Factor, who is 20, in today's Metro:
"What was the first record you bought?
Alexandra Burke’s Hallelujah [released in 2008]. I grew up with music always being in the house so didn’t need to buy it but Alex really inspired me. I was so into her, I bought the single. I really admired her drive and ambition to always do better."
Update - a couple of articles posted on Metafilter address this: First, a young woman who has 11,000 songs, but has only ever bought about 15 CDs. Second, a musician responds.