A couple having children can usually expect that they have an even chance of having a boy or a girl. This is generally true in animals, and even plants, where the sex of an offspring is controlled by the inheritance of a sex chromosome. However, this is not always the case. Tatum Norrell, a 2013 graduate of UF, and Assistant Professor Stuart McDaniel set out to test whether a sex ratio bias could be introduced at meiosis. In the September issue of the American Journal of Botany (http://www.amjbot.org/content/101/9/1572.abstract?etoc), they report that spores from fire moss (Ceratodon purpureus) already show unequal numbers of males and females. What’s more, the biases were common, but favored both male and female spores to varying degrees. What is behind the unequal numbers of male and female offspring? Competition for nutrients from mom or for space to grow later in life may favor fratricidal genotypes that act at meiosis. Although the sexes must cooperate during much of their life, the study by Norrell and McDaniel shows that both males and females may adopt unsavory strategies at the cellular level in the struggle to pass genes on to the next generation.