I was worried about it too before I had my son almost 12 years ago, but unfortunately I don't think there's anything anyone can say to put your mind at ease. Hell, my kid talks fine & I still find myself worrying every now & then after all this time. I think the best way to look at it is to realize that if your children do end up having a problem, at least they're in the best possible hands to cope with it since they've got you. No matter what, I'm sure you'd do anything to give them the support that you wish you had as a child. Having kids is fucking terrifying. If not stuttering, there are literally thousands of other things that can go wrong that you have little to no control over. All you can do is trust yourself to do the best job you can at raising them. It'll all work out in the end.