All the kittens I had were fixed up pretty early (or when I got them from the humane society SPCA, they were fixed up and very early on - around 9 weeks or so) and they were fine. It is humane, because they can then be free to play outside and not get pregnant continually which is also hard on the cat and hard on owners and society. Too many unwanted kittens/cats as it is. Cats also start mating very early on, so some people who intend on getting cats fixed up can get a big surprise! They are often too late. My brother for instance had a kitten, well on her way to becoming a cat and he had all the intentions of getting her fixed and was too late. She got pregnant much earlier than expected. Again, it depends when you allow them outside too. It's not like you'd let an 9 week old kitten go wondering around by itself anyway. So his young cat must have been just old enough to go outside (obviously) but young enough to where he suspected she was safe

There are some who say it's cruel, and can't really give an explanation for why.....because my cats were all female, all fixed up, and all energetic and happy and were allowed to frolic outside. Not kept inside because I was scared they'd get pregnant.

I know someone who said "that's cruel" (about fixing cats up) and they kept their cat indoors permanently and had the cat de-clawed to prevent furniture scratching. So their idea of cruel and mine were obviously VERY different. Not only could their cat no enjoy the freedom of exercising it's claws anywhere, in the case of any emergency, it would not be able to do much protecting of itself, nor would it be able to have much luck gripping and climbing too well if claws were required.

Of course, there are other ways to do this to cats if people want to protect furniture apparently.

I would not like to keep a cat inside permanently as they enjoy trees, outdoors and hunting. Some may do ok, but it's just not my idea of fun for any cat personally. And getting them fixed up does not appear to change any aspect of their personality.

The only problem maybe. E.g. you've had a cat, it's had kittens and you've given the kittens away to good homes and kept one of the kittens. The mother and kitten get along fine. THen you get the mother cat fixed up....suddenly the mother cat does not like her kitten and they wind up fighting like any other cat. They can happen sometimes because the instinct towards the kitten may have changed since being fixed. However, the personality otherwise does not change. Though again, it's possible that the kitten was growing and the mother no longer required the protective element as much anyway, so it may not have been the "fixing up"....but it's possible it was.