Baby born with 15 fingers and 16

                     Baby born with 15 fingers and 16

Since a definite cause for myopia has not been determined, researches are divided as to whether the disease is caused by genetic factors or environmental factors. The debate for the genetic theory begins with the thought that myopia may be due to a dominant gene that is inherited by the child from the parent . There is evidence to suggest that genetic heterogeneity attributes to high myopia. This implies that the child who inherits diversified genes from his or her parents is more likely to develop myopia. However, it is also thought that myopia may be caused by influences from the nervous system that are not normal and have a negative impact on the developing eye.

 Thus, it may, as well, be genetically determined . The basis for the genetic theory is supported by the fact that myopia tends to run in families. The genetic theory has ample evidence for support; however, it has not been directly linked to myopia as a definite cause for its development.Whether or not a gene is dominant isn't the same as whether it is common, and in the case of the gene causing six fingers, it is indeed dominant, but also rare in the population.The gene is likely be rare because historically, people with six fingers have found it harder to find a partner and so passed on their genes to fewer children than their five-fingered neighbors.In modern times however, the sixth finger is removed from a child shortly after birth. Whether this results in an increase in people with six fingers isn't simple to predict - assuming the six-finger gene has no other effects, surgical removal of the sixth finger would remove the selective disadvantage but not confer any advantage, effectively rendering the gene neutral. If the practice of finger-removal was continued over a long enough time for evolution to have an effect, since the six-finger gene is rare it will most likely die out of the population over thousands of years.