Your gynec may be right in this case. You might be a victim of genital warts caused by HPV infection. It can be spread from people of same or opposite sex. It doesn’t matter whether you had anal sex or not. The thing is that you had sex with someone having HPV infection. That infection in turn got transmitted to you, causing anal warts in you. You told that you used to have sex with females only. But it is not sure that any of them has got HPV infection or not. If any of them has got it, you also got infected from them through the straight sex, you had with them. Even condoms fail in providing protection against HPV infection, as it can be spread from warts outside the penile shaft, including anal area. Also, genital warts need not be visible in any of your female partners, as the virus can stay dormant in human body for years without any symptoms. But they can spread through sexual contacts. Even the infected partners do not realize that they are carrying and transmitting the virus. In your case, if your body immunity is good, warts will go away by their own in a matter of one or two years, as they will be defended by your bodily immune system. There are some sorts of medications available to remove warts, if they tend to spread. However, no treatments are available to completely cure the infection. Hope, your doubt is cleared by now. Take care.