You know, I don't know why we have freckles and birth marks.However, I can tell you a little bit more about what they are. Freckles are small yellow to brown colored spots found on areas of the skin exposed to the sun; usually confined to face, arms and back. Birthmarks are small to large skin malformations or blemishes, due to pigmentation or dilated capillaries. That means that the freckles are related to being in the sun, while birthmarks are actual more or less permanent (except some children's birthmarks which go away over time). Maybe you can find out why we develop those and let me know!