Now I really can't decide

So I just spent the weekend babysitting my 2 nephews while my Sister in-law and her husband take a weekend off and yes I'm still alive! Now you might not think the last statement important until I tell you that the boys are only 2 and 3 years old. I could tell you that Jord and I had our hands full, but the truth is that aside from being worn out from all the playing the weekend was awesome! They are the 2 of the best behaved kids I have ever seen. There is of course the occasional altercation where one of them take something from the other one or accidentally gets hit with a hockey stick, but they are otherwise really really good. They nap when the need to, they eat when they are hungry, they are polite, and best of all they go to bed when you tell them and sleep the whole night without any accidents. But this brings me to a point in my life. Having kids. Not that Jord and I are actually considering it, more that I start to think about what my kids will be like. Will they be behaved and nice like my 2 nephews? Or the more likely; will they be like I was at that age? I'm not sure I can handle that. I mean, I had a great weekend, but I'm tired, oh am I tired! What if I had to do that everyday (not just for 2) and they are not as easy to handle? I know I'm just stressing about something I can't control for the most part, and I do believe that when I do have kids, God will give me the strength I need, but still, little me's running around? Scary thought!