There is more evidence to suggest there are genetic/biological reasons behind homosexuality than 'conditioning' or the likes, but nothing has been 'absolutely-confirmed'..
Nathan_Lane_Rules! though, it is quite a controversial conclusion to suggest Musical Theatre caused your homosexuality. The problem is you have no evidence to support your theory but the apparent correlation between homosexuality and theatre...
Not many things are "absolutely confirmed" when dealing with how the human body/mind works. They still aren't 100% sure why most people are right handed, but a select few are left handed. Or what exactly causes cancer and some people develop it (esp those who live a "healthy" life) and those who don't. Weird.
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