Do you live with your mum? I'm not sure what the situation here is--it could be any one of several things; you could be a kid living with their mom, a college-age person paying rent, somebody living in a multiple-generation household, or somebody who's moved in with an elderly parent...
Here's why people are reluctant to get cats:
1. They cost money. Vet care, spay/neuter (your kitten will need this before 6 months; new anesthesia technology makes it possible at a weight of 2 pounds), food, toys, and the 'extras'--cat beds, cat furniture, grooming--that you can get along without (if you groom your cat yourself and don't mind sharing your furniture). If you're financially secure, then you'll be OK, but otherwise, you might need to take on a part-time job to pay for the cat... Assume an expenditure of anywhere from $20-$200 a month, depending on whether or not you're buying anything other than food and litter, and whether your cat goes to the vet that month. You'll need to be sure you can fit the cat into your budget. If you're a teen, you'll have to show your parents you're serious about a cat--get a job, get a bank account, and save up enough so that when you get your kitten, you can pay for its things and first vet visit. After that, the next big expense is neutering; but there are cheap spay/neuter programs (we can help you find the closest in your area).
2. Cats need care. Sure, it's fun to play with a cat, but are you willing to do it every single day? Will you scoop its litter box--every day, without fail? Will you groom it, clip its claws, and feed it on a regular schedule? Can you keep an eye on its health, to head off any problems before they get bad? Fleas, for example... Needless to say, a parent often believes that they will be the one to care for the cat after the initial excitement wears off. This is often true--because while it might be fun at first, eventually they will be chores, just like washing the dishes. However, they won't take long--maybe ten minutes a day--and can easily become a part of your routine. It's a matter of getting used to doing it, maybe at a set time every day like just before you go to bed, or just after you get up.
3. Litter boxes disgust some people. However, what probably got those people disgusted in the first place is a litter box that's scooped only once every other day, or even less--obviously, it will begin to smell! Urine, especially, is a culprit: Urea turns to ammonia, which smells horrible, after a while. And if you have a male cat, and don't neuter him, the litter box will smell extremely bad--if he doesn't spray elsewhere! But all that is easy to avoid: Neuter your cat, and scoop the box every day. I recommend keeping the box somewhere that's easy to sweep up; near the box, keep your litter scoop, a bag of fresh litter, a trash can, and a broom and dustpan or mini vacuum (for cleaning up litter that's tracked or sprayed out by an overenthusiastic digger).
4. Untrained cats often ruin furniture by scratching. And some people, either ignorant, cruel, or indifferent, solve this problem by declawing their cats--but this can cause problems for years afterwards. Declawing means amputating a cat's toes. The pain can be so bad for the cat that it associates scratching in its litter box with pain, and thereafter refuses to use the box. Various health problems, such as infections, muscle spasms, breathing problems, and even death are associated with declawing. So, the alternative? Training. Cats need to scratch to keep their nails healthy and their muscles strong, so you need to give them something to scratch on, something acceptable. Cats have different scratching styles; some like horizontal scratchers, some vertical. Make sure the scratcher is long enough for the cat to get a good stretch in. You can rub the scratcher with catnip (for an older cat), dangle a toy near it, or even take the cat's paws in your hands, if it will allow it, and "scratch" its paws on the post. I've had some success miming scratching with my own fingernails as well. In any case, a cat taught to use a scratching post can be discouraged from using other surfaces by a variety of methods: Tape, sticky side up; foil; bad-smelling (to cats) sprays; or training with a "NO", hiss, or loud clap. If worst comes to worst, you can use claw covers--plastic tips that glue onto a cat's claws, like false nails, and keep it from hurting anything it scratches. These need to be replaced periodically.
5. Some people just don't like cats. A caution: If this person might actually hurt the cat, don't get one--it's not worth it. But if the person just doesn't like, or know, cats, there's a recourse: Assure that person that you are willing to keep their room "off limits" to the cat, keep the litter box clean, and make sure the cat doesn't do any damage. Hopefully they will learn to tolerate each other, or perhaps like each other.