Hilary Duff/Miley Cyrus?

I borrowed my friends Ipod for an upcoming trip because I lost mine in school. I noticed that he has 200 songs but 28 of them are from Hilary Duff and 4 from Miley Cyrus. He has songs from Linkin Park, Akon, Timbaland etc also but I still find it wierd that he likes songs meant for 8-12 year old girls. He is 25 years old. I found that really odd... do you?