Is it normal that i think gay people are right & wrong

Just like there isn't just one single type of straight person, there is far from one single type of gay person. Every gay person has a different life experience, a different sexuality and a different gender identity. Butch gay girls and femme gay guys stand out more from the straight population because they're more apparently "different", but studying/analyzing the gay population as a whole based on the people you know right away are gay is biased because the majority of gays and bisexuals, yes, even in 2015, are not obviously gay or still in the closet.

Of course you're correct about early life experiences affecting sexuality and identity. Like you seemed to suggest, they don't cause the sexual preferences per se, but maybe bring it to the surface. Perhaps gay men who realize they're gay earlier settle into the idea of themselves as different or 'not generically masculine' at an earlier age and come to terms with themselves by being proud of the fact they're different or special. Instead of trying to identify with straight males and imitate them, they might latch on to the feminine side of the spectrum or begin to indulge in superficial interests. It's not that they're inherently masculine and denying it or inherently completely feminine either. Most people are conditioned to follow gender stereotypes, even gay people.

My theory is that most people are born closer to gender neutral and learn to become more manly or girly depending on what they think is expected of them and what will earn them more respect or make them feel like they belong, or what will suit their sexuality or personality traits. I think society starts to tug us toward a specific gender pretty early on, even as early as toddlerhood. Oftentimes our parents or caregivers are our first role models. Obviously gay people can relate to the opposite sex more, being attracted to their own sex, so most would naturally gravitate toward having opposite sex friends and engaging in the traditional activities and characteristics of the opposite sex as well. But I believe it's not always black and white.

Though sexuality and gender identity often exist completely separately, I think sometimes, in some people, the two go hand in hand, and it's probably something to do with brain chemistry. I think there are a lot of people in this world who have brains that aren't wired like their biological gender, and I think that a lot of them turn out gay or bisexual. These people may not have gender dysphoria. They might be OK with having the physical form of their biological gender or may be so borderline androgynous that they don't care enough either way.

Homosexuality includes a wide spectrum of feelings and behaviours that don't just apply to purely homosexual people themselves. Some bisexual people, for example, are, for all intents and purposes, straight, but just open-minded sexually, and on the other end of the spectrum are the people who're attracted to their own sex, but might not see it that way because inside they're really a lot more like the opposite sex, and then there's everyone in between these two extremes, plus nuances and grey areas.

It's complicated, but all we really need to understand is that we need to be tolerant of everyone even if we CAN'T entirely understand them. If you really are as worldly as you claim to be, you'll already have realized all this. You've probably met gay people in all walks of life, and most of the time you wouldn't have known it, and trust me, they all have a different story and a different journey they're on trying to figure it all out and be who they were meant to be, and their sexuality is just a small part of that.

None of that is necessarily right or wrong, it just is and is normal

What I don't understand is why is it okay for them to say that having sex with the opposite sex is gross, but it's not okay for straight people to say it's gross to have sex with the same sex.

Sexuality and gender are complicated. We should try to understand it from a scientific viewpoint because they're influenced by a variety of biological and social factors. There is nothing wrong with being gay. It might be different, but not wrong.