My first pet was our family’s dog. She was actually a part of the family before me- my parents got her as a young puppy, and she was a year older than me. She passed away when she was nearly 17 (RIP Tansy).
I always had some kind of little animals, starting when I was pretty young… Started with some goldfish, which I’d usually win at carnivals. Later I got some frogs/toads, a couple newts (not all at once)

Finally in 5th grade or so, my science teacher’s hamster had babies, so I brought one home. He was a great pet, never bit… I named him Hambrain. Pretty soon after, a friend’s hamster had babies, and I brought 3 home. I caged all 4 together, and you can imagine what happened next… I ended up with generations and generations of hamsters, I think the most I ever had at once was 20 (about 12 were babies). Between me and the friend I got them from, we supplied the whole neighborhood with pets!
It was pretty cool, all the hamsters were so friendly and most never bit, I guess they had good genes. I think I had about 6-8 generations of hamsters. The friend and I tried to make a hamster family tree of all our related hamsters. It was pretty complicated- there were great-uncles and nieces that had offspring, etc… I guess inbreeding isn’t really a problem with hamsters, we never had any bad health problems.

These were Golden hamsters, the odd thing is everyone keeps telling me now that you should NEVER house Golden hamsters together, because they’ll kill each other.
Most of mine lived with other hamsters, I had up to 5 or so in one cage at a time, never hurt each other. When I had the original 4 hamsters, I also bought 2 mice who lived with and got along with the hamsters. I ‘co-owned’ the mice with another friend, and when they would stay at her house, they would be caged with her 2 hamsters (who were related to mine) and they always got along too…
We even had sleepovers where we would bring our hamsters and the mice and they’d all sleep in the same cage, and they seemed to enjoy it.