I am assuming you have antibodies without actually having chronic, or ongoing, hepatitis C virus (HCV) infection. Likely you are among the 15% to 25% of people who acquired HCV and cleared the virus on their own, usually within six months after contracting it. Because the symptoms associated with hep C can be mild or nonexistent, it is possible to have the virus and be completely unaware of it.
Another explanation is that your mother had hepatitis C and passed the virus or the antibodies to you during pregnancy. People usually lose HCV antibodies that have been passed along by the time they are 3 years old. However, occasionally antibodies linger, which may explain your situation. Alternatively, your mother may have passed HCV to you, your immune system cleared it on its own, and you are left with the HCV antibodies.
The bottom line is that some people won’t ever know the source of their hep C exposure. Even if you have a plausible explanation, it is hard to verify this. This link will take you to more information about hepatitis C.