It's essential to approach this topic with sensitivity and understanding. It's not uncommon for young individuals going through puberty to experience a range of thoughts and feelings as they explore their emerging sexuality. Fantasizing about people, including parents, can sometimes occur during this phase.
At around 12 years old, children are undergoing significant physical and emotional changes, and their curiosity about their own bodies and relationships with others may lead to a variety of thoughts and fantasies. These feelings can be confusing and overwhelming for many young people, and it's crucial for them to receive support and education about healthy relationships and boundaries.
While such thoughts are a normal part of development, it's also essential to recognize that boundaries and privacy are essential in family relationships. As you've mentioned, you no longer have those fantasies, which indicates that it was likely a natural phase of development.
If these past experiences are causing you distress or guilt, it could be helpful to discuss your feelings with a mental health professional. They can offer guidance and provide a safe space for you to explore these emotions and address any concerns you may have.
Remember that it's essential to be kind to yourself and to understand that everyone goes through different phases of development. Seeking support from trusted individuals or professionals can be beneficial as you navigate these complex emotions.