In past games, at least, Ditto could breed with males and females alike. That's a very large part of what made it so useful; you say your starter is male? No problem! Breed it with a Ditto until you get a female child! It's actually impossible to get a Ditto egg; the egg will be the non-Ditto species regardless of which gender that parent is (including genderless!) and two Ditto put together don't even breed. I highly doubt they'll change this in DP since Ditto is the only way to breed genderless pokémon like Magnemite and Staryu.