Okay then...
*inhales*
Ectobiology is a science that allows the cloning, breeding and genetic modification of an organism using appearification. Players of Sburb and their ancestors or guardians are created via ectobiology, with the exception of Dad Egbert/Crocker. John performs the ectobiology in the pre-scratch kids' session and Karkat in the post-scratch trolls' session. It would appear that the only known Sburb players not paradoxically created through ectobiology are Calliope and Caliborn, who are the offspring of two adult cherubs. It's unknown if fedorafreak and his server player 2busy4this were created ectobiologically.
Its processes are apparently easily automated, and the Homestuck universe houses several machines dedicated to specific ectobiology tasks. Many of these are in labs within The Veil. Mom is also known to possess a semi-functional one.
John Egbert uses the chumhandle ectoBiologist on Pesterchum, although he was likely unaware that it was a real science. He adopts the handle after Terezi used the term in a conversation with him. Ectobiology coincidentally involves Green Slime Ghosts, more or less.