[Doc, starting to get into this] That really depends on the type of shapeshifter, doesn't it? Whether they have a default form, the limits of their shapeshifting ability -- hell, you might as well pull in the psychological aspect and consider what age the shapeshifter themselves would prefer to look like, their feelings on the aging process --

[Marty, amused] Doc -- probably should remind you you're technically not a biologist either.

[Doc] I've dabbled a little bit! I'm a student of all sciences!

[Dee, snorting] And you wonder why people back home thought you were a little weird.