An authoritative 1989 analysis of genetic technologies by the US National Research Council summarized the scientific consensus: "With classical techniques of gene transfer, a variable number of genes can be transferred, the number depending on the mechanism of transfer; but predicting the precise number or the traits that have been transferred is difficult, and we cannot always predict the [traits] that will result.
Un bien fundamentado y prestigioso análisis realizado en 1989 por el Consejo Nacional de Investigación de EEUU resumió el consenso científico: "Con las técnicas clásicas de transferencia genética, es posible transferir una cantidad variable de genes, dependiendo del mecanismo de transferencia.