Why am i color blind? what is the cause of color blindness? no one in my family has the gene that causes color blindness.

Varies in severity: There are many types, causes, and variations in color vision deficiency. Most types are not treatable, but most are not severe enough to cause a problem with routine activities (unless someone was a graphic designer or artist). The most common type is red-green deficiency, and about 8% of males have this. They have trouble with olives and tans, like in sorting socks. Some are worse than others.

Blame your Mom: If you have red-green color deficiency, then you carry a defective x-chromosome which you got from your mom (i assume you are a male). Your mom was a carrier so she was color normal and you had a 50% chance of getting the abnormal x from her. So in fact someone in your family, mom, had the gene.