M.B.
I did not speak until I was five nor did my father and at least one of his siblings and many others in his family and we all grew up to be very successful and intelligent. My grandma called it the lazy Irish tongue, in her own endearing caustic way. If it helps, I've heard that Albert Einstein did not speak until he was 5 either. :-) My mom was an educator and took me to be tested over and over and finally they said I had a "processing" problem (probably to give SOME type of diagnosis) and I went through a couple years of speech therapy in k-garden and 1st grade. You could have her tested, but I would not worry about it too much, we all made up for it once we started talking.