Probably not a good idea. Our kids are usually smaller than we are, and should use smaller racquets. Since the introduction of the USTA’s 10-and-under tennis initiative, the racquet companies have flooded the market with kid’s racquets. Varying from 19 to 26 inches, there is a good choice for almost any kid.
My best advice is to get them a good one. I know you would start them with an inexpensive, pre-strung aluminum racquet but, once they show an interest, make an investment in a quality graphite racquet for them. They’ll play better and enjoy their tennis more.