The time for double eyelids to appear in children is uncertain and varies from person to person. Some may have single eyelids all the time, some may have double eyelids at birth, and some may have double eyelids for three or four months or even a year or two. Double eyelids are dominant and single eyelids are recessive. If both parents have single eyelids, the baby will also have single eyelids and will not show double eyelids no matter how big the baby grows. If one of the parents has double eyelids, then the baby will have the opportunity to have double eyelids, and the time for the double eyelids to appear is not certain. Some babies are born with visible double eyelids. Some babies are born without double eyelids, over time, the baby’s facial skin and muscles grow and develop before they appear, usually until three or four months, and some will be one or two years old or even later before they gradually appear obvious double eyelids.