What are the boundaries of brotherhood in Islam between a male and a female who have lived together since childhood?

Islam did not base the relationship between a man and a woman on their living in the same place since childhood, but rather on the criteria of lineage, suckling, and affinity. Therefore, Allah forbade a man from marrying his mother, sister, paternal aunt, maternal aunt, father's wife, son's wife, and son's daughter. The Prophet, peace and blessings be upon him, said: "Suckling forbids what birth forbids," and in another narration: "What is forbidden by lineage is forbidden by suckling." And He permitted a woman to display her adornment to those mentioned in His saying, the Almighty: "And not display their adornment except to their husbands, or their fathers, or their husbands' fathers, or their sons, or their husbands' sons, or their brothers, or their brothers' sons, or their sisters' sons." As for their living in the same place, it has no effect, and they are like other Muslims, falling under His saying, the Almighty: "The believers are but brothers."