(Quick warning, the timeline is a little different because of when certain music genres were around).
Regulus Black, who only knew of classical music and was told it was the only music acceptable, and that all other genres were improper.
Regulus Black, who was only taught ballroom dancing and balett because no other type of dancing was heard of in pureblood families, such as his.
Regulus black, who lived like this until one day wandering the halls of hogwarts and hearing strange music being played by muggles, who classified the songs in genres called "heavy metal", "hip-hop", "indie", and more.
Regulus Black, who quickly was obsessed with what he had heard, went against what he was taught since day one and befriended the muggles who played the music that intrigued him to lengths he didn't think possible.
Regulus Black, who was taught by his new friends (who he only saw in private due to obvious reasons), all the music genres and all their subtypes.
Regulus Black, who became even more hyper fixated when he learned that there were other dance styles, some of which belonged to certain music genres.
Regulus Black, who was taught by his muggle friends and even some of their friends how to dance to certain music, which Regulus picked up in no time.
Regulus Black, who continued to learn and practice dancing from any source he could get his hands on.
Regulus Black, who once he faked his death, went fully muggle, and became a famous professional dancer all over the internet.
(I am hoping that someone will write an actual fic like this one day).