P.S.: In my interpretation, on this picture every Blook is a literal ectoplasmical clone of Jake's genetic (not juridic) grandchildren.

(Homestuck: Beyond Canon spoilers ahead)

As such, Mettaton is Harry, Mad Dummy is Yiffy, and Napstablook and Hush Dummy are hypothetical children of either Tavvy, Joey OR Jude.

P.P.S: Lots of people believe that Jude is fedorafreak.

But, according to F.F. himself, his family has died because of Sburb incident.

However, it's safe to assume that Joey and Jude have separated after they grew up. Jude could convince his sister to play online together, so both of them may have strong equipment and a bright future.