Why baby born blind ? why not marry to cousin ?

Hello. : Hello. The issue with with marrying a relative is that there may be some of the same recessive genes for unhealthy traits coming from both people. This would put the fetus at risk for expressing that gene.

Many causes: Blindness in newborns can be from a variety of fetal insults including infections of various sorts. There are also a number of genetic reasons for blindness. These can be increased with the marriage of first cousins which is why this is discouraged.