Some people don't count Order of Shadows as part of the timeline, but if you do, then Christopher is Simon's Great Grandfather and Simon is the son of Desmond, Delores, or Zoe.
I can't remember where, but I think it's stated that Soleiyu was born shortly after Adventure, which makes him 15 in Belmont's Revenge.
1576- Castlevania Adventure, Castlevania: The Adventure Rebirth, Castlevania: The Belmont Legacy
Chris Defeats Dracula
Soleiyu is born
1591- Castlevania II: Belmont's Revenge
Dracula kidnaps Soleiyu(15), possessing him to become evil.
Christopher once again defeats Dracula, and saves his son.
16XX
20 years prior to Castlevania: OoS, Rohan Krause kills the parents of Desmond, Dolores, and Zoe Belmont.
16XX- Castlevania: Order of Shadows
Desmond Belmont enters the forest Eternal Night, defeating Rohan Krause and Dracula with the help of his sisters Dolores and Zoe.
1669
Simon Belmont is born.
1691- Castlevania
Simon Belmont(22) enters Castlevania and defeats Dracula.
In the moments before his death, Dracula places a curse on Simon.
1692
In his pursuit of Dracula’s servants, Simon Belmont(23) finds himself in the Time Rift.
1698- Castlevania II: Simon's Quest
To vanquish the curse, Simon(29) gathers Dracula's remaining body parts and burns them, resurrecting Dracula and defeating him again.