Easy explanation! (Score 5, Funny)

Easy explanation: people in stereotypically male professions, except for jocks, are less able to attract an attractive mate. This sad fact leads them to disproportionately engage in sex using the "doggy" position to avoid looking at each other's ugly faces. And, as has been proven, this results in semen getting in closer to the egg where the male sperm can impregnate. Face-to-face intercourse requires sperm to swim farther, giving the advantage to the female sperm, which have greater stamina and can impregnate after all the wimpy male sperm have died out.