My friend has recently been obsessed with the idea of a character that shares his Experience Points with his minions in order to get him several minions through so far the only things we have managed to discover are golems which are either too expensive or too useless in combat situations. That's when we came up with the idea of using children as minions but any race we managed to find have kids that take a really long time to grow up so we are currently looking for a player race whose kids instantly form into adults. Does anyone have any knowledge regarding such a race?Note that races which eat others souls to breed are not preferred but they will be accepted if there is no other option.
Most creatures that can create fully-formed creatures—either by killing other creatures or by circumstantial division—are inappropriate as PCs for most campaigns
There are many monsters that can quickly transform other creatures into monsters like—or sometimes even wholly unlike—themselves by, essentially, killing those other creatures; such monsters typically have the special ability create spawn like the behimiron, fungus queen, and globster, or the more pedestrian shadow, vampire, or wight. However, I suspect most GMs will discourage players from using such creatures as PCs.
Similarly, some monsters produce offspring by sticking their breeding bits into other creatures and waiting until offspring burst forth from those creatures. Such offspring are sometimes even fully formed. This special ability is often called implant, but it's not a standard special ability—each monster's method is unique. Examples include the gloomwing, the gryph, the tsathar, and the iconic xill. Although it may sound judgy, I think it's safe to say that this is almost always horrifying for everyone (except maybe the monster) both in the campaign setting and around the gaming table, making such creatures ill-suited as PCs in all but the most sinister (or, at least, biologically open-minded) campaigns.
Finally, there are monsters that spontaneously create semi-identical offspring—usually as a result of violence via the extraordinary ability split—, like the black pudding, gunpowder ooze, and schism hydra. Again, I suspect most GMs will discourage such creatures as PCs.
Redistributing earned XP also isn't usually a thing
So far as I'm aware, there's no way that a PC can share his XP with an NPC so that NPC can advance in Hit Dice or class levels. Character Advancement says, "As player characters overcome challenges, they gain experience points. As these points accumulate, PCs advance in level and power." Hence, unless the GM says they do, most NPCs typically just don't gain XP, even if the PC created that NPC and no matter how the PC created the NPC.
(It is decidedly hazy as to how exactly a PC that somehow acquires then uses a special ability like the extraordinary ability split would then function; this GM strongly discourages PCs messing with special abilities like that exactly because of the headaches such abilities cause in the hands of PCs!)
Despite all this, some class features, special abilities, and feats—notably the feat Leadership—provide an NPC that does gain XP for participating in encounters alongside a PC, and this ends up being my suggestion to your friend who wants an army of loyal minions: acquire one or more of those class features, special abilities, or feats that allows gaining an NPC; work with the GM to find an agreeable NPC that possesses a special ability that allows the NPC to create NPCs identical to itself; then have the NPC use that ability on the PC's behalf. As the NPC advances alongside the PC, the NPCs that the NPC can create will increase in power concurrently. While this may not be exactly what your friend wants, the end result will be largely the same.
Note: While I understand your friend's enthusiasm, it's far easier to start a spy network, a self-perpetuating cult, or an apocalypse with the spell create undead than it is to have a PC that possesses an ability like those possessed by this answer's example creatures. That is, while I suspect most GMs will look askance at a player who says that his next PC will be a demonic knight or that his current PC with the feat Leadership is attempting to recruit as a cohort a bonethorn—seriously, the game even removes from the prestige class shadowdancer the create spawn ability of the shadow she can gain via the supernatural ability summon shadow—, the spell created undead often goes unhindered in those campaigns that are even slightly generous toward the necromantically inclined. Really, manufacturing undead would be this player's solution to the problem of acquiring loyal, self-replicating minions rather than picking for his PC's race one that possesses the special ability to create loyal, self-replicating minions.