Owning a gun is a responsibility. Like all responsibilities, it entails work, and time.
First of all, a gun is little use without training. Training in how to use the gun takes time. Will you devote the amount of time necessary? Remember that you want to know how to use this gun instinctively. I am assuming that you mean a handgun–it takes a lot of practice to hit what you aim at even on a well-lit range. At night, in the dark, when you can’t really see, and you have just woken up…..
You absolutely must put a great deal of thought into how the gun will be stored. The last thing that you need is one of the children getting at the gun. How will you store it? Will you have quick and easy access? What means will you use to stop your children from accessing?
You also must give some thought to where you live. What are the laws? What kind of permit do you need?
Do you live in a house? An apartment? Keep in mind that if you miss, the round that you shoot may very well go through your wall, and endanger whoever is on the other side–that could be your children. The type of weapon that you choose is very important, and should be chosen with a great deal of care.
I am not against owning guns (I own several). However this is not something to be done lightly. You should not just buy one, have a few hours of lessons, and then put it in the safe. It is not like riding a bicycle–it takes constant practice.