What are at least three possible challenges Darwin might have faced

I'm assuming you mean Charles Darwin.

1. He would have loved to become a doctor, though he is terrified at the sight of blood.

2. Darwin didn’t publish his findings straight away because he knew that they would be extremely controversial and upset many people.

3. Marrying his cousin was extremely controversial, considering they're family, in two ways, now, though one by choice, which was strange.