Dear Madame L,
It seems to me that when teething, any baby that I can recall grows straight teeth. When those kids lose their teeth and get their "grown up" teeth, it varries as to whether or not those ones are straight or crooked. Why is that? Why aren't the "baby" teeth crooked for the people that end up having crooked "grown-up" teeth?
Those are great questions! Madame L has wondered about that, too, and her Web research has not provided her with a completely satisfactory answer yet. She will ask a friend who is a pediatric dentist for an opinion and provide that later.
In her web research, however, Madame L did learn that not all babies' teeth do come in straight, which surprised her because she, like you, seems to remember every baby she has ever seen having perfect, widely spaced, little bumps of perfectly white teeth. (However, Madame L confesses to having an imperfect and hazy memory about such things, in part because she hasn't looked that closely into babies' mouths for awhile.)
Madame L also learned that crooked adult teeth (and yellowish adult teeth) are thought to be the result of a mouth and jaw not being malformed or being not large enough for the adult teeth and, in general, other hereditary issues.
At any rate, Madame L will find out more as soon as she can, and perhaps persuade her dentist friend to write the explanation.