Pookies don't stay young forever. Some of them "age up", or transition, to the next phase of life.
A pookie is usually zero to eight years old. Nine and ten-year-old pookies are uncommon, but still possible. Older pookies are often adopted from the Pet Shop, but a mumu may wish to have a baby of her own. She can either adopt or lay an egg or have a tummy, which is basically a pookie fetus that follows the mumu around. When the newborn is born or hatched, he/she may turn red and will need to be warmed, cleaned, and clothed.
Newborns will have to sleep in a crib and can only drink milky or formula. Soon, the mumu or duh duh will be able to take the pookie out of his/her crib and he/she may learn to sit up. Pookies from this stage grow very quickly, often going from sitting up to crawling in less than a Club Penguin day. The pookie may start babbling common pookie catchphrases like "Goo!" and "Eh bah!" before actually talking. At this point, he/she will shift from just having milky to eating soft foods like mush mush.
A few Club Penguin days later (depending on the growth rate of the pookie), hair and teeth may start to develop. However, some pookies prefer to not wear a wig in the game as it prevents common items from being worn like the tiara or earmuffs. He/she may start to go to stool. The pookie will often look young for a while, but he/she may start to transition into a middle, depending on the fam fam's playstyle.
A middle is about nine to twelve in human years. They are often the "middle" child and go to "middle" school. To transition from a pookie to a middle, he/she will change clothes to look older and will ditch the tiara in place of a wig. At this point, he/she may develop a new color. Changing colors is like puberty in Club Penguin.
Males become tan and females can be tan or peach. Middles and other fam fam members can be different colors, but its often because they are discolored, new, or innovative. Some middles don't change colors until they are biggies. Middles try to act like older teens but are still kids at heart.
A biggy is basically a middle but with some adult attributes. Biggies are often the oldest child and range from 13 to 18 years old. They are usually very dramatic due to the raging hormones that come with being a teenager. Biggies go to high school and may start to date at this time. They are often are involved in sports and other after-school activities. Some biggies are out of the igloo more than they are in it. Eventually, they will move out. This is usually because he/she wants to go to college.
An adult is a penguin older than 18. Some adults get married or get a job. They may adopt pookies or hold pookie contests. Older adults often have grown-up pookies who don't live with them anymore. They will say things like "walks slowly" or "falls down stairs" and eventually change their look. They may change their hair to blonde or something grayish. Some male adults lose their hair. Sunglasses will often be switched out for regular glasses. Even if he/she doesn't have grandchildren, an older adult is often called grammy or grampy. Inevitably, he/she will die. His/her family may have a funeral. After this, the player starts a new life as a newborn or may haunt the fam fam as a ghost or angel.
- Each Club Penguin year varies depending on the player, but they are typically pretty short. However, pookies and other fam fam members don't celebrate their birthday that often
- Some pookies skip the middle stage entirely
- Some fam fam members don't age at all