In humans there are two sexes: Men and Women. Babies are made when special cells called sperm (produced by men) combine with cells called ova (produced by women) in a process called conception. Each of these cells is produced by a process called meiosis which makes cells containing half the information of the parent. When the cells combine, they form a new cell, called a zygote which has all of the information needed to make a new person. The zygote will grow to become a baby with a unique combination of their father's and their mother's traits.