Hey Emily,
I think I can answer your question. I have thought about this before, and I hope I can help.
First, when God created Adam and Eve, they disobeyed Him by eating the fruit from the tree which He told them not to. God warned them what would happen if they ate it, and since He is good, He did what was right by punishing them for it, like He said He would. I think that letting them choose to eat the fruit or not was God testing them to see if they really loved Him or not.
So anyway, since then, people do get sick, and are born with problems and bad things happen because of sin. Being born gay/pansexual/whatever else just goes along with that. We are naturally inclined to sin. It's the same with a straight person who commits adultery, it is all sin.
And it is not right for anyone to treat people badly, or insult them, since love does no harm to others (Romans 13:10), BUT Christians are supposed to warn others of their sin (Galatians 6:1), with humbleness and gentleness. It is not love to know that a person is in danger of eternal punishment and not warn them about it. I think a lot of Christians have a problem with either warning people in the wrong way or not at all. I am criticized and insulted for being a Christian though every day because I live in a family of non-Christians. They have told me that I'm going to grow up to be a freak, don't be a religious nut, etc.
I do believe it's wrong to be LGBT, because of what I've learned from the Bible, and I'll explain why, however I do believe that some people are born that way, just as some people are born with other things that might incline them to sin. I believe that it is a sin to ACT on it, or to "feed" those desires.
Okay, so now I'll explain why I think being LGBT/acting on it is wrong.
As it says in Genesis, God created a woman for a man. So what I think is that, say, a woman marrying a woman, would be disrespecting God because we're going against how He originally planned things to be. 1 Corinthians 11:3 says:
"But I want you to understand that the head of every man is Christ, the head of a wife is her husband, and the head of Christ is God." So originally God intended for a man and woman to be together, not a man and man or a woman and woman.
1 Corinthians 6:9 says that homosexuals will not enter the kingdom of God.
But, 1 Corinthians 6:11 also says this:
"And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God" (emphasis added).
We can choose to give sin up for God, although I know from personal experience that this is completely impossible without Jesus's help. I had MANY things that I struggled with, and the fact that I was so prone to getting addicted to/obsessed with pretty much anything other than God didn't help at all. After I was saved, I still struggled with temptation, but it's rare for me to give in now, if at all. I chose God over all of those things, because I love Him that much. But it was Jesus that gave me the power to choose in the first place, because anyone who sins is a slave to sin (John 8:34). Also, Matthew 7:21 warns that not all Christians will enter the kingdom of heaven, and it goes on to say that only the one who does the will of God will. It isn't God's will for us to disobey Him.
I will be praying for you, and I hope you make the right choice, as I did (even though it was hard). I really encourage you to study and read the Bible if you don't already, because it helps answer any questions you might have, and for a lot of other reasons. I also really hope that what I said helps you, and I believe that God led me to tell you this, though I'm not sure why yet.