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Are there still "sons of Horus"
(reddthat.com)
The gene seed is still around, so I'd guess so. A common feature of the gene seeds is that a lot of astartes takes on the visual traits of their primarch. You see this mentioned a lot with some other legions, like for example the blood angels having faces resembling Sanginius.
But a lot of the traitor space marines resent Horus for failing during the heresy, so guess it isn't brought up much.