I'm often asked the question if boys take longer than girls to potty train and I say no. Girls and boys take different amounts of time to potty train depending on their personality, depending on their motivation, depending on their ability to learn, and the consistency of the parent. For example, two boys of very different personalities can take different amounts of time to train. If one boy is really excited to get a truck, every time he goes pee in the potty, then he's going to train more quickly than a little boy who isn't so interested in getting that truck, when he goes pee in the potty.
On the other hand, if the girl really wants to be like mamma and use the potty, then she's going to be more motivated to use it, whereas her sister may not be so interested in using the potty because she wants to remain a baby, she wants to remain the younger sister, so she may not be motivated by potty training.
So, it really doesn't depend upon the gender, it's more about the personality and the willingness to get potty trained.