Genesis 34:1-2
"Now Dinah the daughter of Leah, whom she had borne to Jacob, went out to visit the daughters of the land. And when Shechem the son of Hamor the Hivite, the prince of the land, saw her, he took her and lay with her by force.”
Here Dinah did something that was dangerous in those days, just as it is dangerous in today's "modern" world. It would have seemed like a harmless act to her, for she merely "went out to visit the daughters of the land”, maybe to make some friends but, a young women, alone, unescorted, in a unfamiliar city, not a smart idea. It's unclear whether or not her parents knew that she was gone but in the rest of the chapter we see the outcome of her visit.
What had been done to Dinah was terrible in any culture of any time, but the response of Simeon and Levi (sons of Jacob) was simply awful. And nowhere in all this was any real concern expressed for Dinah, their sister. All that had been done in the name of revenge was done for themselves.
The Truth
“Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, “Vengeance is Mine, I will repay,” says the Lord.” (Romans 12:19)