You're asking for reasons not to do it, , so I guess I'll go through them. Not because I think your family might actually do these things, but because they are common pet issues, and well, you asked.

1. Your boys are young I assume? Kids ask for lots of things for xmas that are then quickly forgotten. Do they REALLY want a cat, and understand what a cat entails, or is this just the gift du jour and tomorrow or next week or next month or next year they'll forget all about the cat and want a new xbox console instead?
1a- realize YOU will be taking care of this cat. Its all fine to give the kids chores, but you cant just let it starve when they forget or refuse to feed it daily, or clean the litterbox often etc.
1b- Cats live a very long time. sometimes 20+ years. Thats a very long time commitment for a young child. A family pet is the best arrangement. Think about what would happen to the cat if the boys lose interest- would you be willing to keep it? What about when they go off to college? Too many animals are abandoned because they were bought for children and the parents don't want to take responsibility of the animal when it is forgotten or the child grows up.
2. Cats can have behavior issues. Its not uncommon for cats to pee outside the box. Its one of the main reasons cats are abandoned. Cat pee is stinky and hard to get out of your carpet, clothes, etc. Cats can also be hard to convince to go back to the box, or very finicky about it. they pee outside the box because you moved the furniture and they dont like it, or there's a new baby/puppy/kitty etc, or they dislike their new litter, or the box location is wrong, etc in addition to certain health issues like UTI.
Cats can also cause damage to a home with their claws. Declawing is an option in some countries (I think its illegal in others), but its highly controversial and has significant cons. How would you feel if the cat ruined your new couch? Or caused damage to your home? And if you rent, many landlords require declawing, which might present an ethical dilemma for you.
3. Cats get health issues. You'll need to think about budget, both for routine things like vaccinations, check ups and flea prevention, but also for potential emergencies. Shelter cats in my area tend to have upper respiratory infections for instance, so it isn't even an old cat issues- its something you'd need to always plan for, possibly from day one.
And that is why you should not get a cat.

Of course, I think cats are lovely animals and make fine pets. But they do have drawbacks, and those drawbacks can be deal breakers for some people. If you do get a cat, I would recommend-
-Read up on cats as much as possible. Much has changed since you were young, and they deserve to have an educated owner. Since you say you don't know much about cats, I'd really recommend doing a lot of homework BEFORE you make the commitment.
-Do not get the cat for xmas. Animals do not make good presents. Bringing a new pet into a house around all that chaos and excitement is not good for either the pet or the people. wait until your house is back to normal- decorations are down, routine is back to normal, all the holiday excitement is gone. An animal coming into a new home needs a quite, calm space to do so. If you want to tie in the cat, gift cat supplies, a litter box, cat toys etc. If you aren't 100% sure about getting a cat, you could give books about cat care, a stuffed cat, maybe a visit to a local cat show or time volunteering at a cat shelter. If you do want to "give" a cat, make up a gift certificate good for a cat, with clear parameters set on it. Then involve the whole family in picking out the cat (researching the cats needs, deciding if a certain type of cat is a better fit, etc) and THEN go pick out the cat after the holiday has passed- maybe even a few months later.
- think about some crucial cat issues- do you want an indoor only cat, indoor/outdoor, or outdoor cat? Declawing- yes or no? Educate yourself on cat food and feeding options (grocery brand? natural kibble? canned? canned and dry? Raw? ) All of those can become very heated debates among cat owners, and most you'll want to be clear on from day one.
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