Many people, I take it, are also aware, for example, that Elizabeth, the mother of John the Baptist, was συγγενής (rendered ‘cousin’ at Lk 1:36, NKJV) to Jesus’ mother Mary, which makes Jesus and the Baptist second cousins; that Joseph had a brother Clopas (=Cleopas, Lk 24:16), whose wife is likely Mary of Clopas (Jn 19:25); that their son Simeon was successor to Jesus’ brother, James, as the head of the Jerusalem community of Jesus’ original followers; and, finally, that Jesus had four brothers: James, Joses, Judas, & Simon (Mk 6:3) or James, Joseph, Simon, & Judas (Mt 13:55) and at least two sisters: (Mary [Miriam], Salome, & Anne[?] [Hannah]).
There has been debate on the exact nature of the relationships so described. Broadly speaking there are three views: Helvidian (referring to sons and daughters of Joseph & Mary); Epiphanian (sons and daughters of Joseph by a first marriage); & Hieronymian (cousins). Unless specifically challenged to defend the view (by the presentation of evidence to the contrary), I’ll proceed on the basis that the most natural reading (Helvidian) is the correct one.
One of Jesus’ brothers (Juda[s]) is (in at least two, and arguably three sources) referred to as the twin brother of Jesus. Whether or not this is defensible, he certainly had two grandsons: Zoker & James, i.e. Jesus was their great uncle.
There is also evidence to the effect that the last Jewish Christian bishop of Jerusalem, Judah Kyriakos, was descended at some unspecified remove from Zoker and/or James.
At the furthest remove I have so far discovered for the δεσπόσυνοι (blood relatives of Jesus) is Conon of Magydos, the imperial gardener, martyred in 250-1, for whom the evidence suggests direct kinship to Jesus.
I have not given references for any sources outside the NT here, but I have them for anyone who can read them.
My interest in this is not simply one of idle curiosity. In the thread I mention above, I argue at length that Christians as such are apostates with respect to Jesus. In fact, the word ‘Christian’ (Χριστιανός) is used only three times in the NT: Acts 11:26; 26:28; & I Peter 4:16.
Acts 11:25-6 reads (NKJV):
25 Then Barnabas departed for Tarsus to seek Saul.
26 And when he had found him, he brought him to Antioch. So it was that for a whole year they assembled with the church and taught a great many people. And the disciples were first called Christians in Antioch.
i.e., from the NT itself: Christians are followers of Paul, not Jesus.
A follower of Jesus would be a ‘Nazoræan’ (Ναζωραῖος; see Acts 24:5) as was Jesus himself (Mt 2:23 & passim), which does not, indeed cannot mean ‘of or from Nazareth’, which in Greek is Ναζαρηνός (Nazarēnos), and to the extent that Jerome identifies Nazoræans and Ebionites (cf. Epiphanius on the Nasaræans), who denied Paul and held that Jesus was an adoptive son of God (i.e. born human), it is to be expected that Jesus’ brothers ‘according to the flesh’, particularly James (as leader of the first Jesus community and whom the Ebionites revered), would accept the same, since he would have well known that Jesus was born of Joseph and Mary.
In general, my point is not that Christianity is somehow a flawed religion, but that Christians scarcely know who they’re following, let alone why.
I should add (though perhaps unnecessarily) that I have so far found no corroborating evidence for a visit on the part of eight desposynic princes to Pope Silvester I in 318, nor for the genealogies through the brothers and uncles of Joseph. On the other hand, there appears to be evidence for at least one son to James, Jesus’ eldest brother, namely, Jude ([Judas]; see Lk 6:16), and possibly a second and third, John & Jose, and thereby even for subsequent descent lines amongst the Seleucid hereditary bishops.