Physically advanced means slower social skills?

So my 7 month ols crawls, stands, and is starting to figure out how to cruise along the couch. No doubt in my mind that he will be walking on his own in the next month or so. Someone told me today that babies that are more physically developed have a hard time with speech and are slower intellectually..what do you guys think? Hos half brother is speech delayed and is 4 (also was ahead physically) and can't understand him to well. I'm hoping my baby doesn't have the dame problem because of it.