If one or both of the parents are dark skinned then the genes dictate that you baby will be dark skinned as well and there is nothing you can do to change it. If one parent is Caucasian (white) and the other medium to dark skinned then the baby may have a lighter tanned shade of skin. If both parents are Caucasians and the baby's skin is dark the first thing the parents should do is have the baby examined by their family physician before giving any different foods or any medications to try and change the baby's skin to fair.
