When I was growing up, I always wanted a sibling. But God had another plan for my family and I. I never did get that sibling, but I grew up with a close group of cousins and my best friend and her siblings (all five of them) who treated me like their own.
When I was younger, I was always lonely, and I always envied the kids that had siblings to play with. But now that I am in college, I can see that I was so lucky to grow up in the way I did and I learned a few things about growing up as an only child along the way.
First, being an only child doesn't mean you are always lonely. You just need to surround yourself with your family, and people who can become your family. It, of course, can always be a lonely feeling to be an only child, but you can change that for yourself. You don't need to settle and not put yourself out there to find people that you enjoy being with.
Second, being an only child means that there is no one else for you to blame things on, so be careful.
It also means that you get all of the love from your parents (even when it seems smothering). I am so close with my parents and I'm not sure if having a sibling would change that. But I am so grateful for the relationship I have with my parents.
Being an only child can also make it harder on your parents for you to go away for school, which means that they will always jokingly and seriously petition for you to return home.
Being an only child also means you never have to hear "Oh, I know your sister/brother," like many of your friends most likely do.
Growing up as an only child also made me be a very independent person from a very young age. I was always at camps during the summer, and by the time I went to high school, I had been away from home for almost the whole summer. I would not be that independent person if I hadn't been an only child, I don't think.
Nobody will tell you that being an only child can define you. But it's up to you on how you let it define you. You can let it make you a better person and that person will be even stronger because they're an only child.