Who knows?
A power game? Maybe some deep psychological resistance to some nonsense that has nothing to do with you, but you remind him of some ancient or internal argument? Resentment / jealousy that his child might exceed him at something, no matter how trivial? Maybe he takes it as a personal insult that his own child rejects his life-style? Sometimes a person (especially a control freak) can get a bug up his arse, and once it’s firmly entrenched, no power on Earth will dislodge it.
Good luck.