Before answering your question, it is necessary to reach a consensus; Explain a concept.
Consensus, the "people" mentioned in the question are ordinary people, that is, the "ordinary people" named in the Buddha's education.
Concept, the "sex" mentioned in the question is what Xunzi called "humanity", that is, human temperament, which comes from human consciousness (in short). If people think about external things with consciousness, they will inevitably produce various differences, such as good and evil; High and low; Big-small, and so on, therefore, people's temperament will be consciously divided into good and bad; Or evil. The "sex" named in Buddha's education refers to "self-nature". For the definition of self-nature, please refer to the Heart Sutra: "Neither birth nor extinction, neither impurity nor increase nor decrease. Therefore, there is no color, no thought, no body and mind, no sound, no fragrance, no touch, no vision, even no conscious world, no ignorance, no ignorance and no old age in the air. Without suffering, the Tao is destroyed, without wisdom, there is no gain, and there is no distinction between good and evil.
Here are the answers to your questions:
On the basis of reaching a consensus and clarifying the concept, we can use the Buddha's educational concept to discuss the good and evil of human nature.
The temperament of ordinary people is good or evil, depending on the season; It depends on the cause and the result. For example, if someone hurts the interests of others for his own benefit, he never cares about human nature, evil is evil, and he never looks back, that is, the reason of the season, or the cause and effect; It's the same person. When he is in the interests of his closest relatives, his humanity may be the best, and even when the time is ripe, he can give up his life. Even this result has not escaped the law of causality.
Whether a person's temperament is good or bad depends on cause and effect.
As for what you said, "all beings have Buddha nature", it has nothing to do with good and evil.
This "sex" is not another "sex" and must not be confused.