Reading Mendelian genetics into the Genesis story is ludicrous. The dream story doesn't identify the striped, speckled and spotty males with the actual one-coloured males of Jacob's flock (suggesting recessive characteristics in the modern perspective) -- this is apologetic fantasy. The point of the dream story is that Jacob's god made a miracle to right the wrong.
This makes sense as a distinct (Elohistic?) source (or redaction) because the story of Genesis 30 (J) could make the reader uneasy from a moral (not scientific) perspective. Better to say God blessed Jacob than Jacob fooled Laban.
This also makes sense from a synchronical narrative approach, as Jacob's explanation to his wives who were Laban's daughters. Instead of saying "I have fooled your father" it was way more diplomatic to say "my god corrected the wrong your father had caused to me".
In any case Genesis 30 clearly describes the stratagem as efficient.