We don't have pets. Contrary to popular opinion, this is not actually a form of child abuse, and I would ask that people kindly stop implying as much. Just deal with it.
I always blame our lack of pets on DH's dislike of animals in the house. This is mostly true: if not for him, the kids and I would surely have oodles of cats. (Yep, all three of us are cat people - you'll just have to deal with that too.)
But it's not the whole truth. There are a lot of facets to the whole truth, but for me the biggest reason we don't have pets is... dirt. I like actual dirt (properly, "soil") a lot, but I like it best of all when it stays outside where it belongs, otherwise it transforms into dirt, which I don't like. (No offense, soil - I feel the same way about spiders.) Pets are dirty. Not necessarily soil-y, but dirty. They stink. They shed. They make a mess. They see fit to bring both soil and spiders into the house. They slobber, poop, barf on the carpet, jump on the counters, show you their anuses, and lick their balls then make direct eye contact with you to see if you enjoyed the show.
I'm just not okay with these things in my house. I like a clean house. A very clean house: we got a wool area rug and I can barely keep up with the mess it makes - I'm thinking of having it put down. I'm a clear clean + tidy on the cleanliness Punnet square, which I believe is fundamentally incompatible with pets. Or at least it is if I value my mental health.
On those rare occasions that I wish we had some pets, I simply reframe my view of things. For instance, my hair is basically a pet: it's crazy high-maintenance, it represents a massive waste of resources, and it sheds profusely. Pet! We have mice in the garden compost bin, which are also basically pets: hope you enjoyed your Corn Pops this morning, little buddies. Pet! Heck, the compost itself takes a ton of work... Pet! We have lots of plants, which are basically really quiet pets that make their own food. Pet! Speaking of food, that quarter of beef in the deep freeze is from a domesticated animal... delicious pet! Plus there's always that damn area rug (you already know how I feel about him). Pet! If you think about it hard enough, we basically have loads of basically-pets!
And finally, if all my basically-pets aren't quite filling the void for me, I like to think about my microbiome - the ultimate in non-traditional pets. Unlike other types of pets, this one doesn't need special food, just whatever I'm having is fine; I don't have to worry about arranging care for it when I travel; and it gives back to me in myriad ways that science is only beginning to discover. Thanks, microbiome - you're the best friend a girl could have!