Why do Matthew and Luke contain genealogies of Jesus, while Mark and John do not? Both Matthew and Luke contain genealogies of Jesus, Matthew to Abraham, and Luke to Adam.  However, neither Mark nor John contain genealogies.  What is the reason for this--both for why Matthew and Luke do contain genealogies, and for why Mark and John do not?
I don't think we can ever know for sure as we can't ask them. However I think the answer is probably to do with who they are writing to and what is the purpose of their writing.

Matthew is probably writing to a Jewish audience. For them the Christ has to have come from Abraham &amp; David and so Matthew spends the time to show that Jesus has the credentials to be the Christ.

Luke has probably been employed to write the book by Theophilus (debated if that is the persons name or title). He has been tasked to report on what has happened and what it means - thus it goes into a lot of detail.

Mark seems to be focused on just reporting the facts as they happened. He doesn't need to present the background information on what it means, just runs through the events.

John is in a completely different format than the other gospels. In terms of who Jesus is he is very much focused on Jesus' divinity - not his human family.