They are a separate species so a succubus or incubus is born that way just as much as you or I are born human . I ' m a bit of a biology nut , so in many of my settings I am fairly firm with treating different types of creatures and fully functional separate species , which means a fully fleshed out reproductive cycle . How it works in this case , is a succubus and only be impregnated by an incubus . The child will then be a succubus or incubus depending on the sex of the child . The actual sex between the two of them would usually take place at the center of an orgy of humans , which will provide a large amount of sexual energy to feed the child . A skilled succubus would probably be able to continue to acquire meals even while pregnant , but the norm would be for the incubus to either assist in her seducing humans , or seducing some to bring home to her . In the case that they prefer harems over active hunting , both of their harems would be used to feed the growing child . After birth , the infant would be able to feed completely on the breast milk of their mother as the succubus would be able to convert the sexual energy that they need to feed on into the milk to give to the child . However , this energy doesn ' t keep very well when the milk is bottled necessitating the need for the succubus to breastfeed directly much more than a human woman would be required . Much like human children later develop the ability to eat solid food as they get older , so to do succubi and incubi children start getting the ability to feed on sexual energy directly . This happens later than the transition to solid food , but still occurs before puberty . After this point , they are weened off of breast milk to being bystanders as their parents feed . During this time period , it is normal for the parents to teach their child about hunting and feeding techniques so when they are older they can support themselves . When puberty hits , it has many more effects on a succubi or incubi than it does on humans . In addition to the physical changes of growth , this is when they start to develop their other abilities such as mild shapeshifting and telepathy . The shapeshifting is limited to shifting haireyeskin color and subtle shifts in bone structure while the telepathy is limited to being able to sense arousal levels and what sort of things a particular person is into . These abilities effectively give the succubi and incubi their fangs for hunting . So , puberty is when they start hunting on their own although at this point in time , they can easily turn to their parents for food if they are not successful . At around the same point in development when human children would move out to either go to college or to support themselves , so to do succubi and incubi move out . At this point , they are completely dependent on themselves for hunting and getting meals . Although , it would probably take another decade or two before they are firmly established enough that they would look into having children themselves . This childhood would take place over the same time frame as a human child , although they live much longer than humans as adults . I don ' t have exact numbers decided on but I am thinking in the hundreds of years , maybe even thousands . I will probably end up with around 1 , 000 years as a nice even number . Because of this relatively short childhood compared to their lifespan , they don ' t reproduce very often which also means if humans ever get it into their mind to hunt down succubi and incubi , it will take a while for the population to recover .