It’s certainly genetic, but the chances actually reduce if your child is a female (regardless if the mom stutters, I believe). Based on what you’ve said, I think the chances are between 25-50%. However, most children who stutter “spontaneously recover” at a young age (see study below). Congrats to you and your wife, having children is the greatest gift in the world…regardless of how they speak. https://pubmed.ncbi.nlm.nih.gov/10515508/