The Lemon Children are the creations of the Earls of Lemongrab, whom they refer to as "their boys" after Jake uses this expression. Four of the children that the Lemongrabs referred to by name are Lemonjon, Seed-Wad, Plop-Top, and Lemonhope. In addition, in "Too Old," a Lemon Child whose place card reads "DUKE SUCK-LEMON" is seated next to Finn at dinner. The Lemon Children are all dukes, if this card is any indication of their titles.
When Princess Bubblegum accidentally left behind the secret formula for creating candy life, the Lemongrabs mistakenly believed that Princess Bubblegum wanted them to make all of their food into "more family." In the process of bringing to life a large group of strange-looking lemon children, the earls nearly starved to death along with their new babies.
In "Too Old" they are seen wearing shock collars, most likely put on them by Lemongrab. They are freed by Lemongrab 2 at the end of the episode and subsequently assist Princess Bubblegum, Finn, and Lemonhope in their escape from Lemongrab by piling up under them so they could jump over the front wall.
The Lemon Children have varied appearances, and some resemble animals, plants, or fungi more than humanoids. They are all yellow or green and resemble lemons in some way. Most of them are chubby.
The offspring of the Earls of Lemongrab seem quite young, cannot speak in more than monosyllabic grunts or shrieks, and seem to be unintelligent. Lemonjon is the exception to these rules. The Lemon Children are loyal to the Lemongrabs and support their ideas. Lemonjon showed concern for the rest of his siblings and his fathers. The children that have tails wag their tails when they're happy. In "Too Old," they apparently have the ability to feed themselves without assistance from their parents. They are also given jobs and uniforms. The only Lemon Child that seems to be gifted/smart is Lemonhope.
Lemongrab and Lemongrab 2 love their children, and refer to them as "family", their "children", and borrow a phrase from Jake by referring to them as "our boys". They do not want their children to worry about them while they are away, so they make a point to alert them of their departure. They seem very affectionate with their children, and their children seem to return it. The Lemongrabs see themselves as the fathers of these young fellows. According to the screenshot of Lemongrab's brain, the earls affectionately call their children their "little pooters."