My daughter is left-handed, but can do a lot of things with her right hand (eat, use scissors, etc.). Her father and I are both right-handed, so I guess she fell into the 2% category (chances that she would become left-handed). I wouldn't change anything about her writing abilities. She's also a great artist.
My nephew started off as a lefty, but my sister forced him to be a righty. However, when he played little league baseball, he would always hit from his left side - perhaps some latent lefty tendencies still remained with him.