This is my personal opinion about gay marriage:
The bible states homosexual as a sin so I disapprove it. I don't want to offend anyone here but I can't really think of a pro for gay marriage. As long as they're happy it's a pro. Aside from that there is some cons, for example you wouldn't be able to reproduce. Yes, you could adopt a child but what if the child disapprove of it when they grow up? They might be mad at a young age for not having a mother. So my opinion is that I disapprove of gay marriage.
Shorter answer:
I disapprove of gay marriage, because the bible said it's a sin. The child can get teased at school for it, and might hate that he/she doesn't have a mother.