My 5 year old niece made me so proud today. Her, my sister, and Brother-in-law came over for dinner and not much was on tv, so my parents put on High School Musical 3 for her and as Soon as they did she was like "no I want to watch Doctor Who with Uncle Davy" then ran into the to our computer room and grabbed my Sonic Screwdriver. It was great, my dad hates Doctor Who, and just seeing his face when she did that was great.
I ended up putting on Partners in Crime for her because I figured she'd like the Adipose, she's only scene random episodes of Tennant's doctor but can name all of the companions and tell you what TARDIS stands for not bad for only seeing a hand full of episodes. I wonder how she would take seeing a different Doctor at her age?