I'm the youngest person on my team, and I mean significantly younger, most of my teammates have kids older then I am. So should I be bothered when one of them calls me "kiddo"?

I personally just find that condescending. You are a coworker who likely works on the same projects as them. And it's prevalent in this industry that young devs have just as much talent as we have been coding as a hobby since youth. I say you start calling them grandpa ;)

I think you should just consider it a term of endearment and move on. People are really becoming too sensitive about meaningless/harmless things and you shouldn't contribute to the soft and over sensitive new generation.

I wouldn't let it bother you but at the same time don't allow it to be a parent/child relationship. The respect should be mutual. I was the "kiddo" for a long time. (last one hired for several years) It wasn't until I moved on that I realized the lack of respect that was being given to me by the old devs. When I began working with devs the same age as me and younger I was actually surprised in how I was being treated in a respectful way.

From middle age people it is meant that they like you. Trust me.
I am guessing you work for a very large company - banking or insurance.

doesn't bother me, I stir up my colleagues as much as i get stirred i called my boss a 'professional tool' yesterday lol, just remember as much as you think you might know alot of the old dogs have been in the game quite a while and may be able to teach you some good tricks, so don't take it personally and just try and learn what you can from them.

I used to be in your shoes. While it is a term of endearment, it also is meant to clearly identify that you are less experienced. I would professionaly ask them to stop it as it may affect how other coworkers view you.

It does sound somewhat condescending. I personally work for a small company where all of the guys are like twice my age, most with kids and I certainly wouldn't feel comfortable with that.

nah, just reply "thanks, grandpa! Why don't you have a nap next to the mainframe and leave some room for the new generation!"

could be worse, I'm the only Irish employee and pretty much daily I'm called potato or spud...!