Hang-ups about things including sex are common and can be relatively minor, but they can for some be major and make relationships very difficult.
Mostly such hang-ups relate to aspects of our childhood and might concern for example the strictness of our parents or our school or other experiences.
However our own memories of our childhood can be very partial and can be very unreliable.
This is basically because of two things ;
1. The mind can blank-out, or repress, some childhood memories that it finds unpleasant or negative for some reason.
2. The mind can imagine, or invent, some false childhood memories that it finds pleasant or positive for some reason.
And for a child, reasons need not make as much sense as adult reasons - they can sometimes be 'silly' reasons.
And 'unpleasant' can include some pleasant, or 'pleasant' include some unpleasant.
A good example concerns learning to walk. When we are learning to walk it involves a good deal of falling down and hurting ourselves before we finally master the art of walking properly. It is very rare for the fallings and hurtings to be remembered, and indeed few clearly remember any of the learning-to-walk process. This memory problem is not due to age because the same holds for older children learning to ride bicycles. While conceptual memories that are substantially negative may be blanked-out or repressed, any physical memories involved do remain active. You wake each morning and can walk, or can ride your bike - the physical memories have not been blanked-out or repressed. The only truely reliable childhood memories are these physical memories. If your memory of something in childhood is unclear, then either little happened or some of what happened has been blanked-out. If you think that you DO remember learning to ride a bike as a young child, it can only be a true memory if when older you COULD ride a bike without more learning.
As adults people can have hang-ups based on true childhood memories or on false childhood memories. It is possible to overcome any hang-up, though some may be difficult. The problem is basically the same as overcoming a phobia like fear of spiders. It helps if you can reason through the hang-up with maybe a parent or close friend until you can decide if for you it is irrational and you can face it down or if you can and should stick with it as an OK hang-up. In the end it is for you to decide who you want to be, and you can do that best if you are well informed rather than misinformed so do try to not let any claimed 'expert' misinform you about you or your childhood. As Freud documented, children can develop strong curiosity about the opposite sex that even unfulfilled can lead to selective memory repressions which may later give them very wrong supposings about their childhood.