It's so hard to tell, especially when they are this young. Riley took quite awhile for her color to start breaking and now everyday I seem to notice more. I'm actually hoping she stays on the darker side since Penny is so light. I'd like to have one of each!
I don't think your baby is extra dark or anything; I think she's super cute! You will be amazed at just how much they change. Wait until your kids are a year old or so and then drag these pictures back out! You won't believe the differences!