Is this OCD???

I know thoughts regarding incest are common OCD fears, but all I can find information on is people fearing that they themselves will commit incest. Has anyone ever had fears that a family member is sexually attracted to them, despite a lack of any real, rational basis? Or is that not OCD?

Yes, that can be OCD. While many people fall into one of the clearly defined subtypes of OCD, I think types really are more of a convenience of speech and a tool for psychologists than anything hardcoded into nature. In reality OCD can and will manifest as just about any irrational or obsessive fear you could think of. These fears can also stop, start, be replaced, or change with or without obvious cause.