Stuttering is not a condition its a disorder and its never without symptoms. There are two types of stuttering, Developmental and Acquired, and only Acquired stuttering developes latter in life. Acquired stuttering is typically from some sorta neurological event its never genetic in origin or cause.
Sources:
Yairi, E; Ambrose, N (1992). "Onset of stuttering in preschool children: selected factors". Journal of speech and hearing research 35 (4): 782–8. PMID 1405533
Kuster, Judith Maginnis (2005-04-01). Folk Myths About Stuttering. Minnesota State University.
Yairi, E; Ambrose, N; Cox, N (1996). "Genetics of stuttering: a critical review". Journal of Speech Language Hearing Research 39: 771–784.
