Were more boys or girls born to atomic-bomb survivors? Normally, somewhat more pregnancies terminate in boys than girls in all populations, and this normal preponderance of male births has not been demonstrated to be significantly altered when the parents (one or both) were exposed to atomic radiation. However, when the genetic studies began, it was believed that a person's gender was simply determined. Individuals inheriting an X chromosome from their father and one from their …showed first 75 words of 816 total…

…showed last 75 words of 816 total…makes the prediction of the behavior of a potentially lethal gene on the X chromosome more difficult, particularly if the inactivation is not always random (preferential inactivation of paternally derived X chromosome in extraembryonic tissue while random inactivation in embryonic tissues). Given these developments, most human geneticists no longer accept the simple, early arguments, and contend that prediction of the effects of lethal mutations on the frequency of male births is not possible. ------------------------------------------------------------------------ **Bibliography**