Did you know that there are certain animal species where there are no males only females. This is fairly common among insects and worms but also occurs to a lesser extent in some lizards. Due to only one sex existing the females are actually able to lay eggs without the need of a male (i.e. no fertilization is required).
This method of reproduction is known as parthenogenesis and will almost always leads to the birth of female offspring. As an example the New Mexico whiptail lizard is 100% parthenogenic and has been bred in captivity for many generations with no males at all.