Definitely nothing wrong with being attracted to the same sex. I'm a lesbian, and I've spent my life having people tell me what I'm doing is immoral. In fact, my last girlfriend and I had to break up because her family is incredibly catholic and we were afraid we'd get caught. The reality is that homosexuality is perfectly natural, and actually quite common throughout nature-- not just with humans. There are several theories regarding why it exists in nature, but one of the most common ones is that in social groups (such as wolf packs), only the alpha pair is meant to have offspring. Since they still need other adults to help support and raise the young, homosexuals are crucial to the group's survival since they would not have the same inclination to reproduce, and therefore can focus on helping to raise the alpha's young. This is just one theory, however, and since humans have distanced themselves from the rest of nature, our reasons for the persistence of homosexuality might differ. It's a very interesting discussion, but as I previously stated, it's perfectly natural and there's absolutely no reason to be concerned for your friend <3