{These which hear the word of God and do it} (hoi ton logon
tou theou akouontes kai poiountes). The absence of the article
with "mother" and "brothers" probably means, as Plummer argues,
"Mother to me and brothers to me are those who &c." No one is a
child of God because of human parentage ( Joh 1:13 ). "Family
ties are at best temporal; spiritual ties are eternal" (Plummer)
. Note the use of "hear and do" together here as in  Mt 7:24  Lu
6:47  at the close of the Sermon on the Mount. The parable of the
sower is almost like a footnote to that sermon. Later Jesus will
make "doing" a test of friendship for him ( Joh 15:14 ).