Despite the knowledge that the entire family system plays a role in the development of an individual, research on the disclosure of LG sexual orientation to the family of origin is mostly concentrated on the parental reaction. Siblings are rarely a focus of such research. Thus, the purpose of this qualitative study was to provide an understanding of the experiences of 14 heterosexual biological siblings of LG persons after they learn that their sister or brother is LG. More specifically, this study explored the changing family dynamics with a focus on the sibling of a LG sister or brother and the ways in which sexual orientation disclosure affects the sibling relationship. Data analysis identified ten themes: personal reaction to disclosure, suspecting sibling was LG based on stereotyping, protectiveness/concern, gay equals being different, anger/disappointment in how parent(s) handled LG sibling coming out, sibling relationship changes, increased comfort with having a LG sibling, disclosure of LG sibling sexual orientation to others, dealing with and challenging heterosexism, and changes to self as a result of sibling sexual orientation.