I see a couple of good answers. The rest miss the point. The question, respectfully, misses the point too.

Your wife and children are unlikely to like what you like. They won’t be comfortable with the same things, so the won’t use them as well. You might as well force them all to drive a stick shift because you like it. So, the question of 9mm vs. .45 is the wrong question for a number of reasons.

First, look at the data…not the ballistics data, the what happens when someone is shot with it data. If you look at the ballistics data, the bottom line is that it doesn’t much matter, practically speaking. Sure, 9mm flies flatter, penetrates better, has larger capacity, has about the same energy with modern loads, and it is easier and faster to get back on target for follow up shots. I don’t know why anyone would not want those advantages, by the way. Yes, the .45 is bigger. The 1911 is a nuisance to clean, much loved hammer, but you can get modern design handguns in .45 that are easier to clean, just like 9mm. You just like it, and that means it’s probably a great choice for YOU.

When you look at the what happens to people when shot by various pistol calibers out in the world, you find that there isn’t much difference between the calibers. .22 does great out on the world, by the way. I think Ellifritz is one really good source.

https://www.buckeyefirearms.org/alternate-look-handgun-stopping-power

One interesting stat. is that he found that 60% of people were incapacitated by one shot with a .22 out in the world, while only 51% of people were incapacitated by one shot from a .45. 47% by the 9mm, just to round that out. But how can that be? Our preconceived ideas about things don’t mesh with that. A rattlesnake is a lot smaller than a bear. A bear is scarier, I think. Your limited question betrays a caliber prejudice you have, and it’s not based on data or science. Ask the wrong question and you may get the wrong answer.

Pistols don’t stop an assailant the way most rifles do. Rifles tend to be higher velocity, and they tear tissue remotely. They make a mess, which is much more effective at stopping people. They rip blood vessels and organs. Pistols poke holes. That’s all they really do. “Stopping power” does not really apply to pistols the way it does rifles. Remember, all you are doing is poking holes with them. Does a projectile .45 inches stop people better than one a little less than half its size? We know the answer, and the answer is no. It doesn’t.

But then why does the .22 of all things seem to stop people better than a .45 for goodness’ sake? The assertion sounds obviously silly. Big is better than small, isn’t it? The punchline is that simplistic, shallow thinking leads us all to wrong conclusions now and then. No one is immune. If someone stabs me in the head with a sword or an ice pick, I’m dead either way. We must fight our own preconceived ideas and look for real answers to the right questions.

Your question isn’t really which of two calibers is better. Your real question, I’m betting, is how can I keep my family safer…. Maybe a handgun won’t make one of your people safer. Maybe one of your people will never shoot a person. Then, maybe a taser with projectile pins might be better for them, or pepper spray. That taser drops people faster than shooting them with a pistol in the torso or extremity, by the way. So, we have to again confront our preconceived beliefs. Is a gun always the right answer? I gave my kids guns too, and I trained them to expert level. I’m just making the point. Guns can stop an attack several ways. You may or may not know that just the sight of a gun stops more attacks than shooting people…and I’m not advocating brandishing guns around. I’m not recommending anything. I’m just stating facts and ideas. Look at the FBI data on this. There’s so much politics involved that you may have to dig for the data, but you’ll see. Caliber is just a very small part of tge pistol equation. Yes, FBI switched to 9mm from .40. It makes sense for them. In reality, cost savings is a huge part of that, but the answer for them is not the same as the answer for others.

I know I’ve gone on too long, but I like the subject and I’m giving you a decent response.

Another aspect of this is that people are generally terrible shots with pistols. Police have been found to be only about 20% accurate in shooting in real life incidents. Young people, even kids, involved in mass shootings tend to be over 90% accurate. Police tend to think they can shoot well. Overall, they can’t. Reality. Soldiers are the same. They train on rifles, and there is still a lot to be desired as far as accuracy goes for most of them, but they are much better with rifles. Qualifying on a pistol does not imply any serious accuracy. It’s simply more difficult to be accurate with a very short barrel on a thing that is only held with the hands, so it’s far less stable, and the sights are more difficult for people. When people think they know how to shoot, they are almost always much harder to teach. Women, overall, rarely seem to have that ego issue. So, they learn better. They just do. Training the person is much much more important than what you put in their hand.

So, anyway, I wonder if you are open and flexible minded enough to embrace the real world data, your people’s real capabilities, and come to the conclusions that will work best for you and yours. I hope so. All the best…

https://youtu.be/T6kUvi72s0Y