The third gender would produce both sperm and eggs to grow not life but to build particle that is then injected into the stomach. Meaning the third gender would need a vagina because they have eggs and can give birth, but do not necessarily need a penis. Because their body can produce complicated molecules and feed them into their own stomach, it would allow them to produce better milk from breasts than normally, but in the modern age that is not always needed, and their body can produce molecules to help muscle strength so they could also have no breasts.