Answer 1

His father has not been introduced. The anime suggests he is also a Pokemon Trainer:

His father has not been introduced. The anime suggests that his father was once a Pokémon Trainer who began his journey in Pallet Town, and that he is still living. In the original, he is also confirmed to have a grandfather, and his son (Ash's father) followed his footsteps. An interview with the series' storyboarder confirmed Ash's father is a Trainer on his own journey. According to the same storyboarder, Ash's father may or may not be introduced in the series, depending on its necessity to further Ash's maturity and development as a Trainer.

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Comments

Ash was a product of immaculate conception. how else would here able to perform such miracles as KOing Brocks GROUND/Rock type Onix, with an ELECTRIC type Thunderbolt, from a Pikachu he had just received at an obviously low level that somehow already knew Thunderbolt to begin with?

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thank you mew

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Ash's Father is Professor Oak. Why do you think they are always together when Ash video chats with Oak? lol

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No in all seriousness though in the Battle Dimension season during the episode when they see Spiritomb, one of the villagers has a flashback about a man who sealed Spiritomb in the Key Stone. They say that he too had a Pikachu. In the visual, you see a man with long hair (like Ash's except longer) and mustache. Although his face was obscured by shadow, he did resemble a matured Ash. This is just my own speculation, it is by no means the answer to your question.

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This comment should be an answer .i would upvote this !!!